The ear includes the external, middle and inner ear. The external ear has two main parts, the auricle (also called the pinna) and the 84301002 |External auditory canal structure (body structure)|.
The external auditory canal has the synonym external auditory meatus. The external auditory meatus is not just the external opening of the canal, but rather the canal extending to the ear drum ( 42859004 |Tympanic membrane structure (body structure)|).
The 61671002 |Structure of internal acoustic meatus of temporal bone (body structure)| (SYN, internal auditory canal, is not part of the ear. As described in the FSN, it is an opening in the temporal bone, and is primarily a nerve conduit that anatomically parallel to the external auditory canal.
Distinguishing consistently between lump and mass can be difficult in diagnostic contexts, as the terms are often used interchangeably or lack precise definitions. As a result, lump and mass have, in certain conditions, been treated as synonymous.
Avoid using 'lump' in new content, where more specific terminology is available.
Lump should not be added as a synonym for mass concepts in the Finding or Disorder hierarchies. Existing legacy synonyms and concepts will remain unchanged.
SNOMED CT is arranged as a polyhierarchy. A hierarchy is defined as an ordered organization of concept codes linked together through IS A relationships. Concept codes are linked to their more general parent concept codes directly above them in a hierarchy. Concepts with more general meanings are usually located at the top of the hierarchy and then at each level down the hierarchy the meanings become increasingly more specialized.
Selected SNOMED CT attributes have a hierarchical relationship to one another known as attribute hierarchies. In an attribute hierarchy, one general attribute is the parent of one or more specific subtypes of that attribute. Concepts defined using the more general attribute can inherit concepts modeled with the more specialized subtypes of that attribute.
Domains
The following are the 19 domains arranged in alphabetical order.
The following subhierarchies do not have concept models:
Environment or geographical location (environment / location)
Organism (organism)
Physical force (physical force)
Qualifier value (qualifier value)
Record artifact (record artifact)
SNOMED CT Model Component (metadata)
Social context (social concept)
Special concept (special concept)
Staging and scales (staging scale)
The pages that follow contain tables that are generated from the Machine Readable Concept Model (MRCM). The tables contain Attribute Summaries for those domains with attributes, information on Group(ed), Cardinality, and In-group cardinality, and Range constraints. The MRCM tables in this guide only reflect the ranges for pre-coordinated concepts; there may be post-coordination values that are not reflected in the tables. All MRCM values for concepts can be viewed via the public MRCM browser at .
SNOMED International creates precoordinated content in accordance with the MRCM. For postcoordinated content, extensions should review the MRCM. If the MRCM does not specify that a particular value is allowed for a given content type (e.g., using an observable entity value for |Component| in a postcoordinated expression), then it must not be used in that content type (e.g., postcoordinated expressions). The MRCM rules for postcoordination must be strictly followed. This is important for interoperability, being able to query the resulting content consistently, etc. However, the MRCM does provide the option for extensions to extend or adapt the rules in a controlled way if required (see the last section of ). This includes expanding the ranges and/or adding new attributes where required. This needs to be done carefully to ensure consistency and data integrity between editions.
There are special cases in the MRCM where an attribute may have two rows. This situation is caused by a new cardinality rule: a row for existing/legacy SNOMED CT content and a row for newly created content. The row that is applicable to new content will be marked by a "[New]" notation.
See .
SNOMED CT relies on the rules for usefulness to avoid excessive precoordination (see Scope section of Editorial Guide).
Approved precoordination patterns have been created and are available at: . For additional information about the fields used in precoordination, see: .
Body Structure
The 123037004 |Body structure (body structure)| subhierarchy includes both anatomical structures and morphologic abnormalities
Anatomical site notations for tumor staging (body structure)
Naming Convention for SEP Model
For example,
Liver structure (body structure)
Entire liver (body structure)
Liver part (body structure)
For example,
Anatomical Structure Modeling
Many terms that refer to body systems or tracts are used imprecisely in clinical practice and in medical publications. Ambiguities frequently arise with many of these terms. We have made the following definitions and distinctions in order to achieve internal consistency of the terminology. We recognize that it may not be possible to get universal consensus for the names for each of these concepts. The goal is to be consistent and clear in defining the meaning of each concept and to allow users and system designers to present the terms that best reflect these meanings in their own implementations.
Cell
Modeling of cells expressing antigens
As the cell hierarchy is primitive, careful attention is needed to manually identify and add the appropriate supertypes.
Undifferentiated cell concepts with a single positive or negative antigen expression (e.g. cell vs. lymphocyte or blast) are immediate subtypes of 362837007 |Entire cell (cell)|.
For example,
725316009 |Cell positive for CD1 antigen (cell)| Is a 362837007 |Entire cell (cell)|
Undifferentiated cell concepts with multiple positive or negative antigen expressions should be subtypes of the appropriate cell concepts with those same single and combinations of positive/negative antigen expressions.
Differentiated cells concepts with positive or negative antigen expression(s) should be subtypes of both: a) the differentiated cell concept of differentiation; and b) the appropriate undifferentiated cell concept with the appropriate positive or negative antigen expression(s).
For example,
117507002 |FMC7+ lymphocyte (cell)| should be a descendant of 56972008 |Lymphocyte (cell)| and also 1373072009 |Cell positive for FMC7 antigen (cell)|.
Body structure, altered from its original anatomical structure (morphologic abnormality)
Both subchoroidal and suprachoroidal refer to the same potential anatomic space between the choroid and the sclera. The term lamina subchoroidea of choroid is the same as the lamina suprachoroidea.
In the literature, the term massive suprachoroidal hemorrhage is replacing expulsive hemorrhage and subchoroidal hemorrhage.
Retinal vein
There is not a vein actually named retinal vein. However, SNOMED CT has concepts with the phrase.
For example,
85003000 |Structure of retinal vein (body structure)| has the synonym retinal vein.
280927000 |Entire central vein of the retina (body structure)| has the synonym entire central retinal vein.
Orbital region
371398005 |Eye region structure (body structure)| has a synonym of orbital region structure which subsumes bony orbit, entireeye, and ocular adnexa.
Pathological process (attribute) = Pathological development process (qualifier value)
Therefore, congenital does not need to be represented as the Associated morphology (attribute) target value. Congenital anomaly morphology concepts usually have non-congenital parents.
Concepts from the Morphologic Abnormality hierarchy should not be used in place of concepts from the Clinical Findings hierarchy, even though they appear to refer to similar clinicalsituations.
For example
4147007 | Mass (morphologic abnormality)| is not a finding, but 300848003 | Mass of body structure (finding)| is a finding
Morphologies are used as the values of the defining attributes of findings and procedures. Findings are used to represent the combination of a morphology and a location.
For example
300923002 | Cyst of scalp (disorder)| represents cystic type of morphology that has the location, scalp
Many morphologies have names that could be misinterpreted as implying a process rather than a structure.
Inflammation might mean the structural-morphologic features of inflammation, such as inflammatory cell infiltrates; or it might mean the process that causes the structural changes. Within the morphologic abnormality hierarchy, the structural interpretation is intended, not the process interpretation.
Multiple x morphologies, such as 125291005 |Multiple cysts (morphologic abnormality)|, are currently subtypes of the “X” morphology. The “X” morphology concept represents a class rather than a singular instance, and this arrangement follows the open world assumption of the description logic in SNOMED CT.
For example,
Cyst of upper eyelid does not mean a single cyst on a single upper eyelid. It represents a class of cyst condition that at least appeared in an upper eyelid. This class would also include a cyst condition involving both upper and lower eyelids.
A similar example is how |Retinitis of bilateral eyes (disorder)| is a subconcept of |Retinitis of left eye (disorder)| and |Retinitis of right eye (disorder)|.
Having the Multiple X morphologic abnormality concept as a subtype of the “X” morphology concept allows the disorder concepts defined by these “multiple X” morphologies to be sufficiently defined. One drawback of the current format is that classification results are not complete.
For example,
Multiple cysts of eyelid would not subsume cysts of upper and lower eyelids in the current concept model.
In the future, these disorder concepts may be updated with a more robust representation utilizing cardinality as part of the logical definition. However, this functionality is not available in the reasoner profile of SNOMED CT at this time.
Hernias involve two body structures, one is the hernial opening and the other is the herniated structure. When modeling hernias, use two role groups to represent the body structures and the respective associated morphology for each site. If the herniated structure is not explicit, use the supertype concept for the finding site.
For example,
The concept 50063009 |Femoral hernia (disorder)| is modeled with Finding site = 818983003 |Structure of abdominopelvic cavity and/or content of abdominopelvic cavity and/or anterior abdominal wall (body structure)| to represent the herniated structure.
The endocrine system is composed of the endocrine pancreas, pineal body, paraganglia, paraaortic bodies, parathyroid glands, endocrine ovaries, endocrine testes, adrenal glands, pituitary gland, thyroid gland, juxtaglomerular apparatus of the kidneys, and some diffuse neuroendocrine structures. Certain parts of the thymus produce endocrine hormones, but the thymus itself is not part of the endocrine system.
For those concepts that describe a congenital anomaly that has been repaired and subsequently acquired an abnormality, follow the naming convention of |Acquired abnormality of X following repair of congenital X (disorder)|.
For example,
871598001 |Acquired abnormality of common arterial trunk following repair of truncus arteriosus (disorder)|
Ischemic disorders are defined by a morphology of ischemic structural change. This need not be permanent, but it is assumed that all ischemia results in some structural alterations at the molecular level.
Ischemic heart disease
Ischemic heart disease includes myocardial infarction, myocardial ischemia (without infarction), angina, and other disorders of the heart that have ischemic structural change (reversible or non-reversible) as a defining characteristic.
Coronary arteriosclerosis can, of course, be present without causing ischemia, so coronary arteriosclerosis is not a subtype of ischemic heart disease.
Likewise, there are causes of myocardial ischemia and infarction other than coronary arteriosclerosis, so ischemic heart disease is not a subtype of coronary arteriosclerosis.
Most abscesses are septic, which means that they are the result of an infection.
If a concept's meaning, based on its FSN and text definition, does not specify whether the abscess is sterile or septic, then the concept should not be modeled as septic.
Modeling Abscess in Procedures
The concept's logical definition uses the Indirect morphology (attribute) of 44132006 |Abscess (morphologic abnormality)| and a Direct substance (attribute) of 11311000 |Pus (substance)|.
The word lesion can be used to refer to both structural and functional abnormalities. This makes a subtle distinction between the clinical finding and disorder semantic tags. The majority of lesions in SNOMED CT are in the disorder subhierarchy.
Lesion as a disorder
If a concept refers to a lesion that is a structural abnormality, then apply the (disorder) semantic tag, and model with an 116676008 |Associated morphology (attribute)| of << 52988006 | Lesion (morphologic abnormality)| .
If a procedure refers to a lesion that is a structural abnormality, then model with a 405816004 |Procedure morphology (attribute)| of << 52988006 | Lesion (morphologic abnormality)|.
Lesion as a finding
Lesion concepts referencing characteristics of a lesion are subtypes of 300577008 |Finding of lesion (finding)|.
Imaging-related lesion findings remain as finding concepts.
Functional lesions should not be modeled using values from the 52988006 |Lesion (morphologic abnormality)| subhierarchy.
Since an obstruction describes blockage inside the space of a tubular structure, the Finding site of obstruction concepts should be a value from the 113342003 |Structure of lumen of body system (body structure)| subhierarchy.
For example,
When modeling gastrointestinal tract obstruction concepts, the Finding site value should be a value from the 432899004 |Structure of lumen of gastrointestinal tract (body structure)| hierarchy as the site obstructed is the lumen of the tract.
At present, some but not all anatomy content exists to support this model for tracts, ducts and blood vessels beyond the gastrointestinal tract but is expected in the future.
Sudden cardiac death is a term used in clinical practice. It refers to an arrhythmia that results in sudden loss of cardiac function which, if not quickly reversed, will lead to actual death. The FSN Sudden cardiac death (disorder) is modeled as a subtype of 127337006 |Acute heart disease (disorder)|. It should not be classified as death. Individuals with sudden cardiac death have not necessarily been declared dead and are frequently revived. It is regarded as a subtype of cardiac dysrhythmia.
Pulmonary embolus (PE) refers to obstruction of the pulmonary artery or one of its branches by material (e.g. thrombus, tumor, air, or fat) that originated elsewhere in the body. When modeling embolism disorder concepts with pulmonary in the FSN, the Finding site is 782966009 |Structure of artery of pulmonary circulation (body structure)|.
708079007 |Overdose of illicit drug (disorder)| is modeled without a Causative agent because the term "illicit drug" may have differing local interpretations.
Vaccine-related overdose
Vaccine-related overdose concepts in the Clinical Finding/Disorder hierarchy were inactivated in the January 2020 Release. They were replaced with concepts in the Event hierarchy, see 788094008 |Excessive dose of vaccine administered (event)| and subtypes.
When authoring, determine whether the concept describes an overdose, which is a disorder , or the administration or ingestion of an excessive dose, which is an event.
The addition of new precoordinated content in the Clinical finding (finding) hierarchy that specifies null values, such as 'not recorded', is unacceptable.
There is a use case for recording the reason that data are missing; however, this information should be recorded using a concept from the Qualifier value (qualifier value) subhierarchy rather than a Clinical finding (finding) concept.
New qualifier values of this type should be agnostic as to what data are missing but support the reason why the data are missing.
Cardiologists noted confusion in the placement of Conduction disorder of the heart (disorder) as a broad grouping that subsumed arrhythmias and heart blocks. In common usage arrhythmia refers to a broad set of conditions that include conduction disorders, under which are heart blocks. The concept Cardiac arrhythmia (disorder) is a parent of Conduction disorder of the heart (disorder), and the active referent of the inactive concepts named dysrhythmia or arrhythmia.
For example,
Arrhythmias, like 72654001 |Supraventricular arrhythmia (disorder)|, are under 698247007 |Cardiac arrhythmia (disorder)|
Conduction disorders include heart block, AV block, bundle branch block, conduction delay, and conduction defect, like 418341009 | Atrioventricular conduction disorder (disorder) |. Other arrhythmias were moved from under 44808001 |Conduction disorder of the heart (disorder)| and placed under 698247007 |Cardiac arrhythmia (disorder)|.
Relationship between Observable Entities and NPU codes
Nomenclature, Properties, and Units (NPU) is a coding system and terminology for identification and communication of examination results from clinical laboratories. Please see their website for more information: NPU terminology.
Logically there is a relationship between NPU and SNOMED CT observable entities. A pilot project examined overlaps and possible alignment; further work may be done. However, there is no formally maintained SNOMED CT documentation on this alignment.
The concepts under 116007004 | Combined site (body structure) | should not be used for concept modeling. They do not provide value for the classification of disorders or procedures. These concepts are ambiguous because their intended meaning is unclear, i.e., a combined site could represent any part of two or more sites or all of the referred sites in the description. The combined site (body structure) concepts will eventually be inactivated.
Genitourinary system
The genitourinary system includes the entire urinary system, as well as the genital system. The genital system includes internal genital organs and external genitalia.
Urinary system/tract
The urinary system includes the organs that form and excrete urine, the kidneys, ureters, bladder, and urethra. The male urinary system includes the prostatic urethra (since it is a male urinary outflow structure).
In common usage, urinary system and urinary tract are used interchangeably. However, in SNOMED CT, this is not they case, i.e., they are not synonyms. The two concepts are: 122489005 |Urinary system structure (body structure)| and 431938005 |Structure of urinary tract proper (body structure)|.
Urinary tract proper
The urinary tract proper includes the organs involved in the excretion of urine including the renal pelvis (but not the rest of the kidney), ureters, bladder, and urethra. It is used for disorders affecting the flow of urine (as opposed to its formation) or the urothelium, the lining of the urinary tract.
For example,
41368006 |Disorder of urinary tract proper (disorder)|
249273002 |Finding of urinary tract proper (finding)|
7163005 |Urinary tract obstruction (disorder)|
255150000 |Carcinoma in situ of urinary tract proper (disorder)|
Upper urinary tract
The upper urinary tract consists of the kidneys and the ureters (to the juncture with the bladder). Since upper urinary tract infections include kidney infection, the upper urinary tract must include the kidney.
Upper urinary tract proper
The upper urinary tract proper is the part of the urinary tract proper. It includes only part of the kidney, the renal pelvis, and the ureters.
For example,
25990002 |Renal pelvis structure (body structure)| has a parent, 431491007 |Structure of upper urinary tract proper (body structure)|.
Lower urinary tract
The lower urinary tract, 19787009 |Lower urinary tract structure (body structure)|, is the urinary system below the junction of the ureter with the bladder. It consists of the bladder and urethra. Lower urinary tract and lower urinary system are the same. The male and female specific components are located under male urinary outflow structure and female urinary outflow structure, respectively.
Obstetric and gravid
Obstetric andgravid body structures should not be added inSNOMED CT. Obstetric is a context for a disorder, procedure, or medical specialty that is applied to a body structure during pregnancy, childbirth, or the postpartum period. The context does not change the body structure.
Prostate lobes
The posterior lobe of the prostate is described in newborns but does not persist in the adult. 113295002 |Structure of lobe of prostate (body structure)| includes three lobes, left and right lateral, and medial.
This is an example of a body structure that is used to group related terms.
The concept 707861009 |Structure of skin and/or skin-associated mucous membrane (body structure)| intentionally employs disjunction (inclusive Or). It includes structures in the deep layers, but excludes non-skin mucosal epithelium, e.g., bronchial, gastrointestinal, and genitourinary sites of squamous cell neoplasms. The 400199006 |Structure of skin and/or surface epithelium (body structure)| concept is used to represent the sites of these neoplasms.
Skin and/or skin-associated mucosa is intended for use in dermatology. It is not intended to subsume all mucosal structures, which are under Mucous membrane structure (body structure).
Diseases of the skin
For the meaning of diseases of the skin , refer to the draft of ICD-11: Diseases of the skin incorporate conditions affecting the epidermis, its appendages (hair, hair follicle, sebaceous glands, apocrine sweat gland apparatus, eccrine sweat gland apparatus and nails) and associated mucous membranes (conjunctival, oral and genital), the dermis, the cutaneous vasculature and the subcutaneous tissue (subcutis).
Skin regions, skin of <body part>
Since the phrase skin of finger can mean some or all of the skin of finger (if interpreted as a structure, rather than entire in the The StructureEntirePart (SEP) model , we could use IS-A to represent the relationship between skin of finger and skin of hand. Thus, skin of finger IS-A skin of hand, IS-A Skin structure of upper limb, IS-Askin region. The word region is not used in all of these names, because it may refer to the entire region or a part of a region.
Scalp
Formal definitions of scalp include layers beneath the skin. Therefore we make a distinction between 41695006 |Scalp structure (body structure)| and 43067004 |Skin structure of scalp (body structure)|.
Soft tissue
There are at least three different use cases and meanings, and thus categories, for the phrase soft tissue. They include:
Tumors. Soft tissue gives rise to similar types of neoplasms of mesenchymal stem cell origin, generally called soft tissue neoplasms. This accounts for the inclusions/exclusions of the category. Non-neoplastic masses arising in soft tissue are included in the WHO Classification of Soft Tissue Tumours.
For tumors, soft tissue is defined as non-epithelial extraskeletal tissue of the body, exclusive of the mononuclear phagocyte system, glia, and supporting tissue of various mesenchymal organs. Other explicit inclusions are: fibrous tissue, fascia, ligaments, tendons, tendon sheaths, synovia, bursae, skeletal muscle, smooth muscle, fatty tissue, adipose tissue, blood vessels, lymph vessels, peripheral nerves, sympathetic and parasympathetic nerves, and ganglia, as well as subcutaneous tissue. Skin, skeletal cartilage, pleura, and the pericardium, peritoneum, central nervous system, endocrine glands, and viscera are excluded.
Sites of non-bone disorders and injuries of the limbs, head, neck, and body wall. Skeletal cartilage, as well as all non-bone structures of the limbs, and subcutaneous tissue and fat are included. Skin and lymph nodes are not included. For the head, neck and torso, mononuclear phagocyte system, central nervous system, endocrine glands, viscera, and supporting tissues are excluded.
Structures identified in images. Soft tissue include everything except for mineralized bone tissue and teeth.
When modeling a concept requiring two role groups with the same finding site/body structure but two different morphologies (because a combined morphology does not exist), then those two morphologic abnormalities can be combined to create a new single, combined |(morphologic abnormality)| concept. Keep the newly created morphologic abnormality concept primitive as all morphologic abnormality concepts should be primitive. Limit the combination to two morphological concepts into a single concept; combining more than two morphological concepts into a single combined concept is not permitted.
Example,
If 400067002 |Acantholytic epidermal nevus (disorder)| had the same Finding site of |Skin structure (body structure)| with two different morphologic abnormalities of |Epidermal nevus (morphologic abnormality)| and |Acantholysis (morphologic abnormality)|, then those two morphologic abnormality concepts can be combined to create a single, primitive, morphologic abnormality concept of |Acantholytic epidermal nevus (morphologic abnormality)|. This will prevent modeling with two relationship groups.
Instead of modeling as per this diagram in the stated view with two morphologies of the same finding site:
Model as in the stated view of this diagram with a combined morphology:
Morphologies can be combined to create a single morphologic abnormality concept where doing so creates a specialization of the morphology e.g. 55075001 |Bleeding ulcer (morphologic abnormality)|. Where morphologies are different e.g. abscess and cellulitis, they can not be combined.
This guidance is not being applied retrospectively so the concept 707496003 |Inflammation and consolidation (morphologic abnormality)| will be an exception to this rule as it already exists as a current concept.
Combining morphologies to create a specialization is done when modeling a concept that requires two role groups with the same body structure and two morphology values. Creating a combined morphology concept enables one role group to be used.
Older 'like' content may still use the two role groups. This content would also need to use the new combined morphology value to support correct subsumption.
Neoplasm exception
Subtypes of 108369006 |Neoplasm (morphologic abnormality)| are not to be combined. These morphologies represent histological cell types that are recognized internationally by pathologists, classified by WHO, and aligned with the ICD-O classification.
The morphologic abnormality subhierarchy is located two levels below the Body structure hierarchy with
siblings Apoptosis and Structure resulting from tissue repair process:
SNOMED CT concept
Body structure (body structure)
Body structure, altered from its original anatomical structure (morphologic abnormality)
Structure resulting from tissue repair process (morphologic abnormality)
The concepts in the morphologic abnormality hierarchy represent abnormal body structures.
Leave Primitive
The subhierarchy of 118956008 |Body structure, altered from its original anatomical structure (morphologic abnormality)| is to remain primitive. Authors are not to define morphologic abnormality concepts.
S concepts are usually named x structure (body structure) or structure of x (body structure). E concepts are usually named entire x (body structure) or x entire (body structure). P concepts are usually named x part (body structure) or part of x (body structure).
Lymphatic, Immune, Hematologic, Hematopoietic systems
Lymphatic system / 89890002 |Structure of lymphatic system (body structure)|
Set of structures through which lymph flows. It includes 59441001 | Structure of lymph node (body structure) | and 83555006 | Structure of lymphatic vessel (body structure) |. It supports the categorization of findings, disorders and procedures that relate to the flow of lymph.
Lymphoid system / 122490001 |Lymphoid system structure (body structure)|
Set of structures with groups of lymphoid cells, including those in the intestines, marrow, liver, and other locations, and the lymph nodes, spleen, thymus, and tonsils and adenoids; excludes the lymph vessels. It supports categorization of lymphomas.
Immune system / 116003000 |Structure of immune system (body structure)|
All of the lymphoid system, as well as the mononuclear phagocytic system; the immune system also includes cellular and sub-cellular components involved in cellular and humoral immunity.
Mononuclear phagocytic system / 127908000 |Mononuclear phagocyte system structure (body structure)|
Collection of true macrophages, distributed widely in the body (splenic and lymphoid sinusoids, liver Kuppfer cells, pulmonary alveolar macrophages, osteoclasts, macrophages in serous membranes, and microgliocytes); also endothelial cells that line hematopoietic tissues.
Dendritic cell system / 127909008 |Dendritic cell system structure (body structure)|
Collection of antigen-presenting cells, including the following: epidermal Langerhans, dendritic reticulum, and interdigitating. Class I histiocytoses (Langerhans cell histiocytosis) are disorders of the dendritic cell system.
Hematologic system / 414387006 |Structure of hematological system (body structure)|
Bone marrow, the lymphoid system, the hematopoietic system, and the terminal cells of all lineages of the hematopoietic system (red cells, white cells, platelets, histiocytes, plasma cells, etc.). Disorders of the hematologic system do not necessarily include disorders of the hemostatic system, even though bleeding and thrombosis are usually categorized as hematologic.
Structures and cells responsible for erythropoiesis, granulocytopoiesis, monocytopoiesis, thrombocytopoiesis, and lymphopoiesis. Refers to the immature cellular elements that eventually form the cellular components of blood. The blood itself cannot be strictly part of the hematopoietic system, since this would cause all components of blood to be part of the hematopoietic system (including components like albumin, clearly not hematopoietic). SNOMED CT considers leukocytes, erythrocytes, and platelets the result of hematopoiesis, but not blood-forming, otherwise leukocytosis would become a disorder of hematopoiesis, whereas it can arise simply from a demargination of white cells following stress. SNOMED CT has a concept named 419333002 | Cellular component of blood (substance) |; note that platelets are not actually cells, but are cellular components.
The blood is not necessarily part of the cardiovascular system, nor is it necessarily part of the hematopoietic system. 87612001 |Blood (substance)| is a body fluid, not strictly part of either the hematopoietic or cardiovascular systems.
|Lymph node structure| could be a single node or multiple nodes. A term in single form does not mean it is a single anatomical entity. For example, | Inguinal lymph node structure | represents the lymph node(s) in the inguinal region. It is a representation of the type of anatomical entity. A 'Lymph node group' concept could have two distinctive concepts, e.g. lymph node of a particular classification group, or a group of nodes, representing the lymph node according to different groups in most cases. If it represents a group of nodes, the description should be in the plural form.
SNOMED CT has lymph node concepts per their anatomical locations, e.g. pulmonary, bronchopulmonary, tracheobronchial, tracheal, and esophageal) and concepts for node groups used for clinical staging of lung cancer, i.e., lymph nodes categorized into 14 stations.
Professional societies concerned with the clinical staging of lung cancer have developed at least three different nomenclatures for stations of lung-related lymph nodes. Even though the numbering of the stations is very similar, the inter-relationships between the various node groups are complex, particularly in stations 4 and 10, near the carina and hilar regions.
SNOMED International considers American Joint Committee on Cancer (AJCC) Station 10 , hilar lymph node, bronchial lymph node, and bronchopulmonary lymph node as synonyms. The American Thoracic Society (ATS) Station 10R, the right tracheobronchial lymph node is not a subtype of tracheobronchial lymph node because its definition includes nodes covered by both lower paratracheal lymph node,(AJCC Station 4) and by the hilar lymph node (AJCC Station 10). SNOMED CT uses tracheobronchial lymph node as a supertype of both inferior tracheobronchial (subcarinal) and superior tracheobronchial (a subset of lower paratracheal).
Clinical finding and Disorder Modeling
A disorder is always and necessarily an abnormal clinical state.
In modeling some bacterial disorders, there will be situations where either the organism or the toxin (substance), or both values, are required for the causative agent attribute. The decision is often determined by whether or not the bacteria are considered endotoxins or exotoxins. The most common exotoxins are:
Botulinum Toxin
Enterotoxin
Cholera Toxin
Diphtheria Toxin
Tetanospasmin
Exotoxins are more lethal in comparison to endotoxins, but there are vaccines against many exotoxins whereas there are no vaccines against endotoxins. There can be instances where an infection is present but the disease-causing toxins are not; in this case, model the concept only with the organism and not the toxin substance.
Example,
276202003 |Infection caused by Clostridium tetani (disorder)| is modeled with a causative agent of 30917009 |Clostridium tetani (organism)| only.
In the situation where a disease is caused by both the infection and the associated toxin, model with both the causative agent and the toxin substance.
Example,
76902006 |Tetanus (disorder)| is modeled with a causative agent of 30917009 |Clostridium tetani (organism)| as well as 26159005 |Clostridium tetani toxin (substance)|.
Creating new morphologies
When considering the creation of a new morphological abnormality concept, consider the following:
When the name of a potentially new morphology is the same as the disease, creation of that new morphologic abnormality concept may not be beneficial since it would not be very morphologically descriptive.
Determine if there is benefit in creating a new morphology for a very small number of rarely used leaf nodes. If the new morphology is needed to differentiate two non-leaf concepts, that would be sufficient to create the new morphology. Otherwise, use the nearest existing morphologic abnormality.
Including a body site in a morphological abnormality concept is forbidden unless there is a clear modeling and pathological need.
Iatrogenic
Adding further concepts to the iatrogenic disorder hierarchy is discouraged. Concepts must have iatrogenic in the FSN to be modeled with an IS_A relationship to 12456005 |Iatrogenic disorder (disorder)|. An iatrogenic disorder should remain as a primitive concept if dependent only upon parent relationships to describe the disorder. In cases where the modeling is explicit, e.g. 202762009 |Iatrogenic cervical spinal stenosis (disorder)|, the concept can be defined.
For example,
Figure: Stated view of |Iatrogenic cervical spinal stenosis (disorder)| using IS_A 12456005 |Iatrogenic disorder (disorder)|
The concepts in the 1254795002 |Substance withdrawal syndrome (disorder)| subhierarchy are modeled as direct children of 64572001 |Disease (disorder)| and are further defined using Due to and After attributes of | dependance (disorder)|.
For example,
74934004 |Psychoactive substance withdrawal syndrome (disorder) has a stated proximal primitive parent of Disease (disorder) and Due to and After attributes of Psychoactive substance dependence (disorder).
Stated view of 74934004 |Psychoactive substance withdrawal syndrome (disorder)|:
Inferred view of 74934004 |Psychoactive substance withdrawal syndrome (disorder)|:
The following applies to the subcategory of 118245000 |Measurement finding (finding)|:
Detected and Not detected are used in the FSN, PT, and modeling of measurement findings instead of Present , Positive , Absent, and Negative.
Existing acceptable descriptions with Present , Positive , Absent, and Negative can remain.
Above reference range , Below reference range , Within reference range , and Outside reference range should be used in the FSN, PT, and modeling of measurement findings instead of High , Raised , Elevated , Increased , Low , Decreased , Normal , and Abnormal.
Existing acceptable descriptions with High , Raised , Elevated , Increased , Low , Decreased , Normal , and Abnormal can remain.
Borderline measurement findings are ambiguous and should not be added.
False positive and false negative measurement findings should not be included.
Clinical measurements concerning specific parts of the body should be modeled with a Finding site relationship if an appropriate body structure is available in addition to the role group with Interprets (attribute) and Has interpretation (attribute).
See
Multisystem disorders
Multisystem disorders are often rare conditions. There may be limited information about such disorders, so they should be carefully modeled.
When determining parent concepts:
A multisystem parent concept should be included.
Genetic or inherited disorders should be modeled in the same way as other genetic and inherited disorders.
The manifestations of the disorder must always necessarily be true before assigning the relevant parents.
Attributes must also always necessarily be true.
For example,
702410002 |Iris coloboma with ptosis, hypertelorism, and mental retardation (disorder)| Since the coloboma of the iris is not always present, coloboma would not be explicitly modeled in the relationships.
Some multisystem disorders can be named by their manifestations. The FSN should be descriptive rather than just a list of names.
For example,
717909004 |Bilateral microtia with deafness and cleft palate syndrome (disorder)|
A multisystem disorder with an eponymous syndrome name should be included as a synonym only.
Event Modeling
Event attributes
When modeling an event, be sure to model the event itself and not the outcome of an event. The outcome of an event would be a finding or a disorder.
Causative agent
Although Pharmaceutical / biologic product (product) and its descendants are considered valid values for the Causative agent (attribute) by the MRCM, they are not currently used as values for this attribute in the International Release. The only exception is 787859002 |Vaccine product (medicinal product)| and its descendants, which can be used as valid values for this attribute.
Allowed ranges
The allowed ranges will not prevent some incorrect modeling. Some allowed attributes have not yet been used for modeling in the Event domain. The planned QI project will review the modeling to ensure consistency of use the allowed attributes.
Vaccine-related overdose
For the January 2020 Release, vaccine-related overdose concepts in the Clinical Finding/Disorder hierarchy were inactivated. They were replaced with excessive dose concepts in the Event hierarchy.
When authoring, determine whether the concept describes an overdose, a disorder , or the administration or ingestion of an excessive dose, an event.
Fracture
Fractures should be agnostic as to whether they are pathologic or not, unless specified in the FSN or could only be caused by trauma (e.g. open fractures). Although most fractures are traumatic, there are some pathological fractures. Based on its FSN and text definition, if the word pathological is present, use Pathologic fracture (morphologic abnormality).
Example: Modeling Traumatic vs. Pathological Fractures
Concept
Finding site
Associated morphology
21351003 |Fracture of phalanx of foot (disorder)|
Bone structure of phalanx of foot
Event
Definition
Examples
Occurrences impacting health or health care; not procedures or interventions
Core body temperature is the temperature in the deep tissues and internal organs, including the brain. The gold standard site for measuring core body temperature is the pulmonary artery. Other sites for measuring core body temperature include the nasopharynx, esophagus, bladder, gastrointestinal tract, and vagina. Some peripheral sites are commonly used to estimate core body temperature but are not a true representation of core body temperature on their own, e.g., axillary region, inguinal region, sublingual space. Body surface temperature is measured at several sites, e.g., skin, foot, spine.
For example,
698831002 |Core body temperature measured in nasopharynx (observable entity)|
415882003 |Estimated core body temperature measured in axillary region (observable entity)|
364518005 |Temperature of foot (observable entity)|
Mass vs Weight
The Property (qualifier value) hierarchy contains the following:
118538004 |Mass, a measure of quantity of matter (property) (qualifier value)|
726527001 |Weight (property) (qualifier value)|
Very rarely is the physics definition of weight used. When the term weight is used, it is most often referring to mass , as further demonstrated by the units of measure i.e., grams, kilograms, etc. Unless units specific to the physics definition of weight are specified using Newtons, assume that mass is implied.
To summarize, always use the mass qualifier value unless a concept is requested with Newton units that specifically refer to weight.
Representing LOINC Terms with the SNOMED CT Observable Entity Model
Logical Observation Identifiers Names and Codes (LOINC) terms are defined using the Observable Entity model in SNOMED CT as produced in the LOINC - SNOMED CT Cooperation Project releases.
The project release documentation contains information about how LOINC terms and parts are aligned with SNOMED CT concepts using the model.
The Susceptibility template is a disposition observable; there is no simple template at this time.
Naming Convention for Digits of Hand and Foot
Fully specified names and preferred names should use proper names of digits of hand and foot. The names by order of digits can be added as optional synonyms. The order of fingers is different from the order of digits of hand because the thumb is not a finger in SNOMED CT. Therefore, the order of the finger should not be used to avoid potential confusion.
FSN
PT
SYN
SYN
Nervous System
The nervous system has two parts, central and peripheral.
The central nervous system, sometimes also called the neuraxis , consists of the brain and spinal cord. The pyramidal system is a subdivision of the central nervous system; the extrapyramidal system is part of the brain.
The peripheral nervous system includes all neural structures outside the central nervous system.
The nervous system is also divided as: autonomic, somatic, and enteric.
Tumor morphology
SNOMED CT accepts tumor concepts, as long as they are included in the International Classification of Diseases for Oncology (ICD-O). ICD-O has two coding systems for coding the site (topography) and the histology (morphology) of the neoplasm:
Topographical - Anatomical site of origin or the organ system
Morphological - Tumor cell type or histology and behavior, i.e. malignant versus benign
The topography code describes the site of origin of the neoplasms. The morphology code describes the cell type of the tumor and its biologic activity, in other words, the characteristics of the tumor itself. The morphology code, combined with the appropriate topography, expresses the complete morphological assessment as stated by the pathologist.
Although the behavior of a neoplastic morphological type is implicit knowledge in the pathology community, the behavior (benign, in situ, uncertain behavior, or malignant) must be included in the description in SNOMED CT to aid users, terminology authors, and mappers; and because over time, the behavior of a certain neoplastic cell type may change depending upon the latest scientific understanding, so clarity is important.
Combining Morphologic Abnormalities
When modeling a concept requiring two role groups with the same body structure but two different morphologies (because a combined morphology does not exist), then those morphologic abnormalities can be combined to create a single morphologic abnormality concept. Keep the newly-created morphologic abnormality concept primitive, as all morphologic abnormality concepts are primitive.
For example
Naming Convention for Cells Expressing Antigens
Order antigens numerically first.
For example,
732279009 |Cell positive for CD3 antigen and positive for CD4 antigen (cell)|
NOT
Genetic, developmental, congenital, and physical origin
The following figure shows the structure of genetic, developmental, and congenital categories, along with non-genetic, non-developmental, and postnatal categories. A dimension, called extrinsic physical force , is included to distinguish deformations from malformations. The sections of the diagram represent categories formed from the combination of the dimensions, each which represents the answer to one of the following questions:
Is it genetic or not?
Is it developmental or not?
Mental health
Dependence-related concepts which express the current existence of abuse are acceptable.
For example,
191816009 |Drug dependence (disorder)|
Dependence-related concepts which express the pattern as either continuous or episodic are not acceptable.
Unacceptable patterns:
Human Genes
Human genes are represented as cell structures (subcellular structures) within the Body structure hierarchy. This reflects the biological reality of genes as physical, organized, functional units within chromosomes.
This approach is consistent with the Foundational Model of Anatomy, the Sequence Ontology, and the HUGO Gene Nomenclature Committee's (HGNC) defining characteristic of chromosomal location. It enables participation of gene concepts in the full SNOMED CT concept model, including hierarchical classification, relationship-based definitions, and use with existing attributes such as FINDING SITE and INHERES IN.
Genes are named according to the HUGO Gene Nomenclature Committee (HGNC).
FSN: <HGNC Approved Name> gene (cell structure)
Osteoarthritis
396275006 |Osteoarthritis (disorder)| is primarily a degenerative disease, although recent research has identified an increased role of inflammation as an inciting cause. Because of this, 396275006 |Osteoarthritis (disorder)| should now be modeled with a morphology that represents both the inflammatory and degenerative aspects of the disease, 1343602002 |Degeneration and inflammation (morphologic abnormality)|. According to many authoritative sources, osteoarthritis is now regarded as an inflammatory disease, and is now a subtype of arthritis.
SNOMED International uses a number of primary authoritative sources to guide the definition of concepts. For the disease hierarchy, UpToDate () is used as a primary authoritative source. As of November 2024, according to this site, “In the past, οѕteоаrthritiѕ (ՕΑ) was considered to be simply a degenerative "wear and tear" process and therefore often misnamed as degenerative joint disease. However, the pathogenesis of ՕΑ is much more complex than just wear and tear and the term "οѕteоarthritis," where "-itis" is indicative of an inflammatory process, is indeed correct .” Additional recent academic articles also confirm the inflammatory nature of OA.
Respiratory System
321667001 |Respiratory tract structure (body structure)|. In SNOMED CT, respiratory tract has the same meaning as the Nomina Anatomica term apparatus respiratorius , which includes the structures through which air passes from the nares to the alveoli. The oral cavity is not included. In common usage, respiratory system may have the same meaning as respiratory tract ; but not in SNOMED CT. Respiratory system does not mean the global respiratory system that might include the CNS components of breathing. Pleura are part of the lower respiratory system, but not a part of the lower respiratory tract.
This phrase has several meanings. The SNOMED CT concepts 119253004 |Upper aerodigestive tract structure (body structure)| and 361922007 |Entire upper aerodigestive tract (body structure)| have the meaning based on the following reference: Cancers of the upper aerodigestive tract constitute approximately 4% of all malignancies. These include cancer of the lip, tongue, major salivary glands, gums and adjacent oral cavity tissues, floor of the mouth, tonsils, oropharynx, nasopharynx, hypopharynx and other oral regions, nasal cavity, accessory sinuses, middle ear, and larynx (Upper aerodigestive tract cancers, Cancer 1995 Jan 1;75 (1 Suppl): 147-53). This definition matches the tumors included in the CAP Cancer Checklist for upper aerodigestive tumors. The esophagus, or at least the cervical esophagus, may be included, but not in SNOMED CT .
58675001 |Upper respiratory tract structure (body structure)| includes the nasal cavity, paranasal sinuses, nasopharynx, oropharynx, and larynx
Nutritional intake observable entities
Naming conventions for estimated and measured intake or nutrient administration, in aggregate or as a portion of intake via a specified route (ie, oral, gastroenteral [enteral nutrition], parenteral nutrition, and via intravenous fluids), is as follows:
FSN: [technique] quantity of intake of [substance] via [route] in [timeframe] (observable entity)
SYN: [technique] quantity of intake of [substance] via [route] in [timeframe]
See the specific template: .
For example,
789106008 | Estimated quantity of intake of phosphorous in 24 hours (observable entity)|
Remission
< X> disorder in remission concepts require a stated relationship to the appropriate primitive Disorder in remission supertype, in addition to the appropriate supertype for the disorder.
For example,
16270831000119107 |Bulimia nervosa in partial remission (disorder)| has stated parents of 698698008 |Bulimia nervosa in remission (disorder)| and 765207007 |Disorder in partial remission (disorder)|.
Where the primitive supertype for the disorder is |Disease (disorder)|, only the Disorder in remission supertype will be required.
For example,
91856007 |Acute lymphoid leukemia in remission (disorder)| has only one stated parent of 765205004 |Disorder in remission (disorder)|, because a potential supertype of 64572001 |Disease (disorder)| would be unnecessary.
Observable Entity Modeling
When observable entity concepts have been given a value, they behave like clinical findings, with respect to the concept model for context.
When observable entity concepts have not been given a value, they behave like procedures, with respect to the conceptmodel for context.
The observable entity model has been implemented in limited content areas in SNOMED CT thus far. Most of the content in the hierarchy is primitive.
Over 165 observable entity concepts have been modeled describing physiological measurements (body temperature, respiratory rate, heart rate, blood pressure). Most of these are sufficiently defined using the attributes. |Vital sign (observable entity)| has been inactivated since it could not be universally defined.
Neoplasm Observables
Observable entity concepts representing histopathology examination observables of neoplasms are being modeled according to a series of templates.
Please see the templates listed here: See the area for more information about the project.
Concepts containing a primary malignant neoplasm from the observable entity subhierarchy employ the 704321009 |Characterizes (attribute)| with the target qualifier value of 1234914003 |Malignant proliferation of primary neoplasm (qualifier value)| in order to define primary (which matches the target value of the Pathological process (attribute) used by concepts in the Disorder hierarchy).
For example,
1136681000004107 |Anatomic location of excised primary malignant neoplasm (observable entity)| applies the Characterizes (attribute) with a target of Malignant proliferation of primary neoplasm (qualifier value).
Stated view of 1136681000004107 |Anatomic location of excised primary malignant neoplasm (observable entity)|:
Stated view of 372087000 |Primary malignant neoplasm (disorder)|:
Trauma and Injury
There is a need to represent both traumatic and non-traumatic injuries as well as those in which it is undetermined whether the cause of the injury was due to trauma or not. There are forms of trauma that do not result in structural damage, such as emotional trauma , which are defined as traumatic injuries.
Concepts that do not specify trauma are now modeled with the appropriate morphology concept or <<Damage (morphologic abnormality) but are not necessarily assigned a Due to (attribute) of Traumatic event (event), unless the form of injury can only occur with morphologic trauma. In other words, if a concept refers to an injury, and that injury may occur either through trauma or non-traumatic means (e.g. tumor, ischemia, etc.), then it should be modeled without a Due to (attribute) of |Traumatic event|. If, however, the term does not specify trauma, but the type of injury can only occur as a result of trauma (e.g. open wounds), then these concepts would have the DUE TO attribute added.
Historically, injury concepts have been modeled in SNOMED CT as damage to a body structure, unless specifically stated as non-traumatic. 19130008 |Traumatic abnormality (morphologic abnormality)| has been inactivated effective January 2021 in order to separate mechanism of injury (i.e. trauma) from structure (i.e. damage).
Malformation, deformation, anomaly
The word anomaly is, by itself, ambiguous as it may mean either a structural or functional abnormality, depending on the body structure to which it is applied. Concepts using the term anomaly must be evaluated to determine whether it represents a structural or functional abnormality. Using the term "anomaly" in new concept FSNs is not allowed. The terms "structural abnormality" should be used when it is unclear whether the morphology results from malformation or deformation.
A deformity is a structural abnormality that is due to an extrinsic physical force. Newly created concepts representing a deformity should be considered disorders.
A malformation is a structural abnormality that results from intrinsically disordered development.
For example,
Co-occuring Genomic Disorders
If the phenotype is always caused by a specific genotype, there is no need to include the cause in the FSN or clarify with a Due to relationship.
Modeling for germline mutations causing conditions, such as cystic fibrosis, should have mutations, Occurrence = congenital, and Due to (attribute) the mutation finding.
For example,
Cystic fibrosis due to G542X mutation
Somatic mutations leading to cancer, such as malignant melanoma with BRAF V600E mutation , should have dual supertypes , including the malignant disorder and the somatic mutation, and Due to (attribute) with the associated somatic mutation finding.
For example,
Hematologic and lymphatic conditions
There is more than one meaning of hematologic. A definition based on hematological system _ structure includes hematopoietic and lymphoid structures (including bone marrow, spleen, thymus, lymph nodes, etc), as well as the cellular components of blood. Hematologic neoplasms clearly fit this definition.
A definition based on clinical usage by hematologists is broader. Disorders of hemostasis and thrombosis are often managed by hematologists, but these do not have a common structural overlap with the lymphoid and hematopoietic systems (with the exception of platelets and megakaryocytes). For clarity, hematologic disorder is a navigational concept that is used to define a reference set that includes disorders of blood and blood forming organs, as well as disorders of hemostasis and thrombosis, depending on what is intended.
Hematologic disorders may refer to disorders of: hematopoietic cell origin; blood forming organs (bone marrow, lymph nodes, spleen, thymus, and other lymph tissues); cellular components of blood; or function of hemostatic and thrombotic systems.
Diseases of the blood forming organs (bone marrow, lymph nodes, etc.) can be defined by any one or a combination of the following:
The morphology (neoplastic diseases, at a minimum, include those morphologies covered by neoplasms in the International Classification of Diseases for Oncology, ICD-O).
Observable Entity Naming Conventions
Naming conventions for the fully specified name (FSN) for observable entities and for naming evaluation procedures or observable entities that are submitted with names from the IFCC-IUPAC NPU systems are as follows:
General naming pattern: Property, Component, Direct Site
First: Property
Property (the property type of the observable) is named first, when possible.
Rheumatoid arthritis
Rheumatoid arthritis (RA) is a multisystem, inflammatory, autoimmune disorder; the exact etiology is unknown. RA is a disease primarily of the joints and is clinically known as an 'arthritis' although extra-articular manifestations occur. Extra-articular features include nodules, carditis and pericarditis, vasculitis, lung disorders, and other manifestations.
69896004 |Rheumatoid arthritis (disorder)| remains a primitive concept in SNOMED CT and must be stated as a parent (IS A relationship) for all rheumatoid arthritis concepts.
For example,
201776007 |Rheumatoid arthritis of sacroiliac joint (disorder)|
Example of extra-articular rheumatoid manifestation,
28880005 |Rheumatoid arthritis with carditis (disorder)|
Poisoning
When modeling poisoning disorders, ensure that the disorder being described is caused by the substance or active ingredient in the product selected as the causative agent (attribute) value. Do not add poisoning disorders if the causative agent is a product constituent (e.g. adjuvant, carrier, preservative, flavoring, stabilizer, or other inactive ingredient) that cannot be identified as the causative agent.
Vaccine-related poisoning concepts have been inactivated.
Enteritis
The term enteritis is broad and commonly refers to inflammation of the intestine, especially the small intestine. However, in some conditions, e.g. phlegmonous enteritis and regional enteritis, the term enteritis refers to any part of the digestive tract.
Thus, all descriptions of enteritis must stipulate the specific body structure that is affected to avoid potential misinterpretations and incorrect modeling.
For example,
Enteritis of intestine
Enteritis of small intestine
X with single episode
X with multiple episodes
Current episode of X
First episode of X
X with continuous pattern
Unacceptable legacy concepts:
Drug abuse, continuous (disorder)
Episodic drug abuse (disorder)
Concepts describing full or partial remission are acceptable but not the phase of the remission.
Acceptable patterns:
X in full remission
X in partial remission
For example,
46244001 |Recurrent major depression in full remission (disorder)|
5703000 |Bipolar disorder in partial remission (disorder)|
Unacceptable patterns:
X in early full remission
X in sustained full remission
X in sustained partial remission
Conditions with associated symptoms should be expressed and modeled like combined disorders. Due to situations are acceptable but not simple Co-occurrent.
For example,
703850002 |Delirium due to benzodiazepine withdrawal (disorder)|
Concepts containing X without Y are considered on a case-by-case basis.
Acceptable example:
724735003 |Oppositional defiant disorder without chronic irritability-anger (disorder)|
Unacceptable example:
Bipolar type II disorder with current episode moderately depressive without psychotic symptoms
Hematopoietic system / 57171008 |Hematopoietic system structure (body structure)|
Modeling
Hematopoietic should be differentiated from hematologic , since the terminal cells of each lineage (the erythrocyte, segmented neutrophil, monocyte, histiocyte, platelet, mature T- and B-cells, plasma cells, etc.) are not strictly hematopoietic.
82094008 |Lower respiratory tract structure (body structure)| includes the tracheobronchial tree (from the trachea through the terminal bronchioles) and the lungs, including the alveolar respiratory tract (which extends from the respiratory bronchioles to the alveoli).
400141005 |Lower respiratory system structure (body structure)| includes the lower respiratory tract and the pleura.
The interarytenoid fold forms part of the inlet of the larynx. The fold has two surfaces, one forming part of the wall of the supraglottic larynx, the other forming part of the wall of the hypopharynx (the food tube behind the larynx, leading to the esophagus). The 102295003 |Structure of hypopharyngeal aspect of interarytenoid fold (body structure)| may be considered part of the hypopharynx, the larynx, or both. A tumor of this site is categorized as a tumor of the hypopharynx, and not the larynx, but the 105585004 |Interarytenoid fold structure (body structure)| is considered part of the larynx.
SNOMED CT does not give a Part of relationship between the hypopharyngeal aspect of the interarytenoid fold and the interarytenoid fold. This emphasizes SNOMED CT modeling based on the relationship of anatomical entities and disorders and procedures and not simply by reading term names.
SNOMED CT differentiates between the bone underlying the nasal turbinates and the actual turbinates:
Bones underlying the turbinates,
118648008 |Inferior nasal turbinate bone structure (body structure)|
122491002 |Middle nasal turbinate bone structure (body structure)|
122492009 |Superior nasal turbinate bone structure (body structure)|
122493004 |Supreme nasal turbinate bone structure (body structure)|
Turbinates, which include bone, overlying mucous membranes, and other tissue,
The 118648008 |Inferior nasal turbinate bone structure (body structure)| is a facial bone and skull bone. And, parts of the ethmoid bone form the middle, superior, and supreme nasal conchae. This means that the bones of the middle, superior, and supreme turbinates are not bone organs.
Representing two associated findings in a single concept may be convenient for recording; however, the representation of the two notions should be recorded separately.
For example,
Breast cancer occurring with positive estrogen-receptor assay should be recorded in the information model as two separate concepts
Somatic NSV (NCBI structural variant) co-occurring and poly-etiologic : BRAF V600E positive melanoma
Somatic IHC (immunohistochemical) finding co-occurring but not etiologic: Estrogen-receptor status in breast cancer
The term phrase, "co-occurrent and due to" is no longer to be used in the fully specified name. There are existing concepts that use the co-occurrent and due to pattern, but these will be re-termed. Genetic mutations that cause a disorder are by definition co-occurrent, so there is no need to represent this in the FSN, but they should be modeled as co-occurring, i.e. supertypes for both conditions should be present.
For example,
118599009 |Hodgkin's disease (disorder)| has 128930002 |Hodgkin lymphoma - category (morphologic abnormality)|. The body site involved (especially specific lymph node groups or skin sites).
For some disorders, like T-cell lymphomas, and plasma cell and immunosecretory disorders, it is important to distinguish those defined by morphology, site, or manifestation.
T-cell lymphomas can be subcategorized according to the primary site, a lymph node, the skin, or other extranodal site. This means that a site of lymphoid structure cannot be the defining characteristic of the parent concept T-cell lymphoma. Its defining attribute should be morphology alone.
Plasma cell and immunosecretory disorders (e.g. monoclonal gammopathy, heavy chain disease, Waldenstrom's macroglobulinemia) are defined by their manifestations, i.e. the type of monoclonal protein they secrete. Others (e.g. myeloma, plasmacytoma) are defined by their morphology, regardless of whether or not they are secretory.
Immunosecretory disorders may have a morphology of plasma cell neoplasm , even though no mass has been identified and the monoclonal protein may be the only evidence that there is a clonal neoplasm.
In general, lymphoid and myeloid neoplasms can be modeled with their morphologies, but without a site. Leukemias and myelodysplastic syndromes are modeled with Finding Site, bone marrow structure (body structure).
There is more than one meaning of coagulation. A broad meaning, to stop bleeding, is better described as hemostasis. A more narrow definition, limited to the formation of the fibrin clot, might exclude certain components of hemostasis (e.g the ability to stop hemorrhage through the actions of blood vessels, collagen, endothelial cells, and platelets, in the absence of clotting). Individuals with congenital fibrinogen deficiency cannot form fibrin clots, yet their bodies are able to stop bleeding. Therefore, coagulation disorders are kinds of hemostatic disorders.
Hematologic disorders, lymphoid and myeloid neoplasms
Coagulation, hemostasis, thrombosis
Modifier: Scale Method.
Scale Method refines the Property, and, therefore, precedes the action in the naming order. (Scale Method, Property)
Naming pattern: (Scale Method, Property), Component, Direct Site
Second: Component
Property is named first, followed by the entity that is the value of Component, when possible.
Third: Direct Site
Modifier: Time aspect. Time aspect provides information about the direct site and precedes it in the naming order. (Time aspect, Direct Site)
For example,
416125006 | Concentration of hemoglobin in erythrocyte (observable entity) |
Serology and serologic test are ambiguous terms and should not be included in FSNs. These terms can be included in the descriptions for antibody observable or evaluation concepts but cannot be included in the preferred term. Existing content will be fixed in a future release.
Measurements done by screening should be specified with by screening method added at the end of the description.
Additional concepts using observable entity attributes have been defined since the January 2020 release. The majority of the changes are related to nutritional intake (e.g., food intake, vitamin intake, fasting pattern) observable entity concepts.
Susceptibility observables should be modeled in accordance with the specified templates.
Naming convention for the structure of digits of hand
Index finger structure
Naming convention for the structure of digits of foot
The autonomic system is further divided as sympathetic and parasympathetic. The autonomic system is not entirely a part of the peripheral nervous system, but the autonomic nerves are peripheral.
The word nerve has multiple meanings according to the FMA:
nerve trunk
neural organ (trunk plus branches, excluding nuclei, ganglia, and roots)
neural tree organ, including nuclei, ganglia, roots, etc.
A neural tree organ is defined in FMA as a nonparenchymatous organ which has as its parts an aggregate of neurons (nuclei or ganglia) and their axons which are grouped into fasciculi by connective tissue to form elongated, cable-like structures that are arranged into a tree. A nerve , according to FMA, is defined as a segment of a neural tree organ which has as its parts a nerve trunk and its branches; together with other nerves of the same tree, it constitutes a neural tree. The neural tree structure includes:
Cranial nerve
Complex cranial nerve-tract
Spinal nerve
Spinal accessory nerve (strictly neither cranial or spinal nerves)
Peripheral nerve
Autonomic nerve
Nerve , conventionally has two meanings:
An anatomically distinct nerve trunk (without branches) that is identified in a dissection (e.g. the structure that student identifies when a pin is placed in the trunk of the vagus nerve, for instance located on the arch of the aorta)
A larger anatomical entity which supports a related set of functions (e.g. all anatomical components of the vagus nerve that are necessary for it to execute its functions (e.g. when a student is asked which nerve is responsible for slowing the heart the answer, the vagus nerve , includes the vagal nucleus, as well as the trunk and branches of the vagus).
Neural tree designates the second concept in order to distingiush it from the first which is only a part (subdivision of) the vagal neural tree.
A third meaning of nerve, defined by the FMA is: Segment of neural tree organ which has as its parts a nerve trunk and its branches; together with other nerves of the same tree it constitutes a neural tree.
For example,
Chorda tympani, digastric branch of facial nerve, greater petrosal nerve, posterior cutaneous branch of posterior ramus of cervical nerve, superior lateral cutaneous nerve of arm.
If one severs the facial nerve, the meaning refers to the trunk. But if one has facial nerve palsy, the meaning refers to the entire distribution of the nerve and the functions served by it.
Cerebrum may refer to the supratentorial brain, which is everything except the midbrain, medulla, pons, and cerebellum. In this interpretation, the telencephalon and diencephalon are in the cerebrum. On the other hand, cerebrum may only refer to the parts derived embryologically from the telencephalon, the cerebral hemispheres and the intercerebral commissure (corpus callosum and anterior commissure).
Supratentorial brain may be used for categorizing tumors and for designating the location of swelling that can result in herniation. The telencephalon and diencephalon (including thalamus, geniculate bodies, pineal body, habenulae, and hypothalamus) are definitely supratentorial. The upper part of the midbrain (mesencephalon) is also supratentorial. SNOMED CT excludes all midbrain structures from the supratentorial brain.
There were several concepts with the phrase x nerve and its branches, interpreted as meaning _ the entire nerve and its branches._ Therefore, x nerve and its branches would be a duplicate of entire x nerve , when we interpret entire x nerve as being a neural tree organ.
For example,
Entire facial nerve
Supratentorial brain
SCT intends to avoid adding concepts that conflate the localization of a specific tumor type in a topographic location as opposed to a neoplastic cell type that is derived from a specialized cell in an organ, e.g. adenocarcinoma vs. renal clear cell carcinoma. One is general; the other is specific to a cell type.
The naming pattern utilized for gene-derived neoplastic morphology terms will align with the WHO Classification of Tumours (IARC 'Blue Books'). Gene acronyms are not required to be expanded. This policy is an exception to SNOMED CT's requirement for expansion of acronyms.
For example,
1186933006 |SMARCA4-deficient undifferentiated tumor (morphologic abnormality)|. The gene SMARCA4 is not required to be named with the expanded form of SWI/SNF Related, Matrix Associated, Actin Dependent Regulator Of Chromatin, Subfamily A, Member 4.
Another example is 1076491000119102 |Nontraumatic complete rupture of muscle or tendon structure of rotator cuff of left shoulder (disorder)|.
If this disorder had the same finding site of |Structure of rotator cuff of left shoulder (body structure)| with two different morphologic abnormalities of |Nontraumatic rupture| and |Complete rupture|, then those two morphologic abnormality concepts can be combined to create a single, primitive, morphologic abnormality concept of |Nontraumatic complete rupture (morphologic abnormality)|. This will prevent modeling with two relationship groups.
Cell positive for CD4 antigen and positive for CD3 antigen
Named antigens follow in alphabetical order.
For example,
1373093007 |Cell positive for CD10 antigen and positive for FMC7 antigen (cell)|
NOT
Cell positive for FMC7 antigen and positive for CD10 antigen
Include “positive”/”negative” for each antigen individually. Do not group by positive or negative expressions.
For example,
1373277009 |Cell positive for CD4 antigen and negative for CD25 antigen and positive for CD127 antigen (cell)|
NOT
Cell positive for CD4 and CD127 antigen and negative for CD127 antigen,
The PT includes the “shorthand" expression. This terming is commonly used in the domain.
For example,
1373277009 |Cell positive for CD4 antigen and negative for CD25 antigen and positive for CD127 antigen (cell)| has a PT of “CD4+CD25-CD127+ cell”
1373093007 |Cell positive for CD10 antigen and positive for FMC7 antigen (cell)| has a PT of “CD10+FMC7+ cell”
Include an acceptable description of the FSN minus the semantic tag.
If appropriate, include an acceptable description with the expansion of a gene name, and include the word antigen.
For example,
Note: Not all existing content conforms to this guidance.
Fully specified name
Preferred Term
Additional descriptions
See also
Is it present at birth or not?
Is it due to an extrinsic physical force or not?
The relationships of genetic, congenital, developmental, and acquired disorders
Explanation of Figure
The sections with diagonal hashed lines represent combination categories that do not occur.
For example, there are no genetic disorders that are due to an extrinsic physical force. Likewise, there are no congenital disorders that are considered non-developmental.
The sections with blue crossing lines represent congenital malformations; they may be either genetic or non-genetic.
For example, congenital infectious malformations
The red circle represents congenital genetic malformations.
The blue sections represent acquired , i.e. disorders that are non-genetic and not present at birth.
For example, Vitamin D deficiency (rickets) in children is a non-genetic, non-congenital, developmental malformation.
The white sections represent genetic congenital or genetic postnatal disorders.
For example, Huntington's disease is a genetic disease that is neither congenital nor developmental. The gene defect is present at birth, but the disease does not manifest until adulthood.
Arrows leading from the sections point to examples of disorders for the category.
Developmental is a useful label for disorders that affect developing structures or functions that may occur pre- or postnatally. They may be present at birth or develop later.
The term familial may also be ambiguous when used for broad categories. It may mean that the disorder is found in higher proportions in the immediate or extended family compared to other groups. Or, it may mean there is a possibility of a disease being inherited. It may be used; however, it may require clarification of meaning from the requestor. It should not be used as a synonym for genetic.
It may be a challenge to classify a condition as a 32895009 |Hereditary disease (disorder)|. Hereditary requires case-by-case definition; it cannot be applied to broad categories. Nevertheless, the names by which many diseases are known include the term, and it is permitted, as long as it does not introduce ambiguity.
Only add gene if the HGNC Approved Name does not already include it
Case sensitivity = CS
PT: <HGNC Gene Symbol> gene
The HGNC gene symbol is always UPPER CASE (alias and previous symbols may contain lower case letters)
Case sensitivity = CS
All HGNC Alias symbols must be added as additional descriptions.
The case sensitivity for approved gene names must conform to HGNC naming conventions. Approved names and symbols may be found at https://www.genenames.org/. Note that most HGNC approved names begin with a lowercase letter; the SNOMED FSN should retain this initial lowercase. This is an exception to SNOMED CT policy for descriptions and will generate a warning in the Authoring platform.
Human genes are modeled with the following two IS A relationships:
382391000210108 |Gene structure (cell structure)|
Exception: Proto-oncogenes must be a subtype of 1396287006 |Proto-oncogene structure (cell structure)|
The specific Chromosomal band structure identified in the HGNC chromosomal location field
Structure of chromosome band <X> (cell structure)
If the specific band does not exist, it must be created.
Each concept must include an attribution to the HGNC URI of the gene symbol report, stored as an attribution annotation.
Example 1: Elastin gene
Example 2: Apolipoprotein B gene
Previous symbols and alias symbols are added to gene concepts, followed by the word gene, where they are unique to a specific approved gene name. Where the same previous or alias symbols appear on multiple genes, they are to be omitted.
Naming
Case Sensitivity
Modeling
Attribution
Previous symbols and alias symbols
FSN: Estimated quantity of intake of phosphorous in 24 hours (observable entity)
PT: Estimated quantity of intake of phosphorous in 24 hours
Figure 1. Stated view of 789106008 |Estimated quantity of intake of phosphorous in 24 hours (observable entity)|
"Dietary" is considered ambiguous and should not be included in SNOMED CT. Existing content that includes "dietary" will be considered for inactivation.
Figure: Stated view of 91856007 |Acute lymphoid leukemia in remission (disorder)|
Figure: Stated view of 16270831000119107 |Bulimia nervosa in partial remission (disorder)|
Concepts containing a metastatic malignant neoplasm from the observable entity subhierarchy do not use 704321009 |Characterizes (attribute)|, but instead are defined by the specific metastatic morphologic abnormality. For example, 444384007 |Number of regional lymph nodes containing metastatic neoplasm in excised specimen (observable entity)| has the attribute 246093002 |Component (attribute)| with a target value of 14799000 |Neoplasm, metastatic (morphologic abnormality)|.
Concepts containing a metastatic malignant neoplasm from the observable entity subhierarchy do not use 704321009 |Characterizes (attribute)|, but instead are defined by the specific metastatic morphologic abnormality. For example, 444384007 |Number of regional lymph nodes containing metastatic neoplasm in excised specimen (observable entity)| has the attribute 246093002 |Component (attribute)| with a target value of 14799000 |Neoplasm, metastatic (morphologic abnormality)|.
Concepts containing a metastatic malignant neoplasm from the observable entity subhierarchy do not use 704321009 |Characterizes (attribute)|, but instead are defined by the specific metastatic morphologic abnormality. For example, 444384007 |Number of regional lymph nodes containing metastatic neoplasm in excised specimen (observable entity)| has the attribute 246093002 |Component (attribute)| with a target value of 14799000 |Neoplasm, metastatic (morphologic abnormality)|.
The terms colorectal and colorectum, commonly used by pathologists, are included in descriptions for concepts referring to neoplasms modeled with 1285733009 |Structure of cecum and/or colon and/or rectum (body structure)|. 1285733009 |Structure of cecum and/or colon and/or rectum (body structure)| is needed because neoplasms are the same from the cecum to rectum and are considered as a group in cancer synoptic reporting protocols. Note, there is no consensus concerning the definition of colon in the literature and between different domains.
Traumatic injuries are now being modeled as morphologic changes to a body structure due to traumatic event.
Non-traumatic injuries are being remodeled as morphologic changes to a body structure but without a |Due to (attribute)| relationship to |Traumatic event (event)|. Nontraumatic injuries should be modeled as a subtype of 1119219007 |Nontraumatic injury (disorder)|.
417163006 |Traumatic or non-traumatic injury (disorder)| is currently modeled with GCIs to reflect the two notions of damage without trauma (non-traumatic injury) and trauma with or without damage (traumatic injury).
Where a request for a specific traumatic or non-traumatic disorder is made and there is support in literature for both, then concepts representing both the traumatic and non traumatic forms together with a generic form should be added.
An injury due to friction can be represented using 400152004 |Friction injury (morphologic abnormality)|, in which case it will not classify as a kind of wound.
However, most disorders that are named abrasion imply that skin or other tissue has been abraded (scraped or worn away). Thus, they are also considered wounds and will correctly classify as wounds after assigning the correct morphology, 400061001 |Abrasion (morphologic abnormality)|.
For example,
211039006 |Abrasion of skin of chest (disorder)|
While many medical definitions refer to abrasions as superficial injuries of the skin and subcutaneous structures, the term is also used for areas such as dentistry to define superficial excoriations of teeth, ophthalmology, and also can be used for other integumentary structures such as nails. The FSN should clearly identify which structure the concept refers to and where this structure is skin, this must be specified.
Ruptures are modeled with an |Associated morphology (attribute)| of 125671007 |Rupture (morphologic abnormality)|. A disorder concept modeled with a Rupture (morphologic abnormality) classifies as a subtype of 417163006 |Traumatic or non-traumatic injury (disorder)|.
Traumatic rupture concepts are modeled with a |Due to (attribute)| of << |Traumatic event (event)|
Nontraumatic rupture concepts are modeled as a subtype of 1119219007 |Nontraumatic injury (disorder)|
The use of |Spontaneous event (event)| is in development, as many of the concepts that related to non-traumatic are not in fact spontaneous.
In those cases where it is clinically apparent that the cause is spontaneous, the concept is modeled with a |Due to (attribute)| of |Spontaneous event (event)|.
In those cases where it cannot be determined that the clinical condition is actually spontaneous (i.e., no known underlying mechanism), a |Due to (attribute)| relationship to |Spontaneous event (event)| would be omitted.
Friction injury, abrasion
Rupture
Congenital anomaly of is currently modeled as a structural abnormality but is not the same as Congenital malformation (structural abnormality due to intrinsically disordered development present at birth). Therefore, it can be regarded as having the more general meaning of structural abnormality present at birth.
When referring to a broad term to denote an intrinsic structural abnormality (e.g., Structural abnormality of fetal bladder) and plan to include 49755003 |Morphologically abnormal structure (morphologic abnormality)| in the model, use the pattern Malformation of fetal X or Congenital malformation of X.
410795001 |Juvenile rheumatoid arthritis (disorder)| has been inactivated with an inactivation reason of Outdated with a target replacement of 410502007 |Juvenile idiopathic arthritis (disorder)|. Subtypes of Juvenile idiopathic arthritis (disorder) are now modeled to reflect the up-to-date classification of this disorder.
Figure. Stated view of 201776007 |Rheumatoid arthritis of sacroiliac joint (disorder)|
Figure: Stated view of 28880005 |Rheumatoid arthritis with carditis (disorder)|
Body Structure Attributes Summary
When authoring in this domain, these are the approved attributes and allowable ranges.
For all Anatomical structure (body structure) concepts, Laterality is an approved attribute which can be populated with the range of qualifier values including Side (qualifier value) or its subtypes.
Digestive System
Digestive tract is the same as alimentary tract, and includes the entire passage for food through the body, including mouth, oral cavity (both vestibule of mouth and cavitas oris propria), oropharynx, esophagus, stomach, duodenum, jejunum, ileum, colon, rectum, and anal canal.
Digestive system includes the digestive tract, as well as the associated organs of digestion, including tongue, teeth, salivary glands, liver, exocrine pancreas, gallbladder, and biliary tract.
Gastrointestinal tract has two meanings in common usage. One that does and one that does not include the esophagus. The usage that includes the esophagus would more correctly be named esophago-gastrointestinal tract. Endoscopists frequently use this meaning, even though it is contrary to some dictionary definitions and does not follow strict lexical interpretation (which does not include the esophagus).
Upper gastrointestinal (GI) tract. When describing upper GI bleeding and upper GI radiographic and endoscopic procedures the upper GI tract includes the esophagus, stomach, and duodenum. The upper GI tract does not include the more restricted stomach-intestine entity.
Lower gastrointestinal (GI) tract. When describing lower GI bleeding, lower GI radiographic and endoscopic procedures, and lower GI output from ileostomies and colostomies, the lower GI tract includes the jejunum, ileum, cecum, colon, rectum and anal canal. The ligament of Treitz may be used as the division between upper and lower GI tracts (and the division between the duodenum and jejunum).
Also, since the upper GI tract is said to end at the duodenum-jejunum junction, and there is no concept meaning middle GI tract, the jejunum can be inferred to be in the lower GI tract.
See J Vasc Interv Radiol 9:747 for an example of inclusion of the jejunum and distal tract as part of the lower GI tract.
The SNOMED CT concepts 119253004 |Upper aerodigestive tract structure (body structure)| and 361922007 |Entire upper aerodigestive tract (body structure)| have the meaning based on the following reference: Cancers of the upper aerodigestive tract constitute approximately 4% of all malignancies. These include cancer of the lip, tongue, major salivary glands, gums and adjacent oral cavity tissues, floor of the mouth, tonsils, oropharynx, nasopharynx, hypopharynx and other oral regions, nasal cavity, accessory sinuses, middle ear, and larynx (Upper aerodigestive tract cancers, Cancer 1995 Jan 1;75 (1 Suppl): 147-53). This definition matches the tumors included in the CAP Cancer Checklist for upper aerodigestive tumors. The esophagus, or at least the cervical esophagus, may be included, but not in SNOMED CT.
Biliary tract includes the gallbladder, intrahepatic and extrahepatic bile ducts, and common bile duct. It does not include the liver. SNOMED CT uses biliary system as a synonym for biliary tract. SNOMED CT has another concept that does include the liver, 732049009 |Entire liver and biliary system (body structure)|.
Mouth has several different meanings including mouth region, oral region of the face, and rima oris.
Mouth region includes structures surrounding the oral cavity, as well as structures of the oral region of the face.
Use mouth region for most disorders with a finding site of mouth.
Oral region of face includes the skin and subcutaneous tissue of the lips and perioral region, the orbicularis oris muscle, and the vessels and nerves in these structures.
Rima oris is the opening of the mouth.
The four regional parts of the tongue are the ventrum (inferior surface), dorsum, root, and body. The root of the tongue is the posterior third, the dorsal surface of which forms the anterior wall of the oropharynx. The root of the tongue rests on the floor of the mouth. The nerves and vessels that supply the intrinsic muscles of the tongue traverse the root of the tongue.
The terms colorectal and colorectum , commonly used by pathologists, are included in descriptions for concepts referring to neoplasms modeled with 1285733009 |Structure of cecum and/or colon and/or rectum (body structure)|. 1285733009 |Structure of cecum and/or colon and/or rectum (body structure)| is needed because neoplasms are the same from the cecum to rectum and are considered as a group in cancer synoptic reporting protocols. Note, there is no consensus concerning the definition of colon in the literature and between different domains.
Clinical Finding and Disorder
Hierarchy
Definition
Example
Clinical finding
Normal/abnormal observations, judgments, or assessments of patients
167222005 | Abnormal urinalysis (finding) |
Disorder
Clinical findings or observations are the active acquisition of subjective or objective information from a primary source. This includes information acquired from human observers, through recording of data via the use of scientific instruments, or indirectly from samples taken from the source, and evaluated separately.
The default context for a Clinical finding concept is:
Present (vs. being absent)
Subject of the record (the patient)
Current, if not specifically stated or specified to a time in the past by an entity linked to the concept
The term observations should not be confused with Observable entity. Observable entity is the name of something that can be observed and represents a question or assessment (e.g. |systolic blood pressure|, |color of iris|, |gender|) which can produce an answer or result.
Given differences in information models, a finding about the subject of the record may be captured in different ways. For example, the information may be captured using either an Observable entity concept together with a value, or a Clinical finding concept which represents what is being observed together with the result of the observation. To assist the transformation between these concepts, if when adding a requested Clinical finding concept, the modeling requires an Interprets relationship, and the Observable entity concept does not exist, then a new Observable entity concept should be created.
The Clinical finding hierarchy contains the subhierarchy of Disorder. Concepts that are descendants of Disease (disorder) are always and necessarily abnormal clinical states. The Disease subtype allows diseases to be subtypes of other disorders, as well as subtypes of findings.
Concepts with a semantic tag of disorder , must have a parent of Disease (disorder) or subtype of Disease (disorder).
For example,
95617006 | Neonatal cyanosis (disorder)| has the parent, Disease (disorder). Neonatal cyanosis is also a subtype of 3415004 | Cyanosis (finding)|
The distinction between a disorder and a finding may be difficult to define. There are, however, distinct characteristics of each.
Hierarchy
Characteristics
In some cases the disease process is irrefutable, e.g., meningococcal meningitis. In others an underlying disease process is assumed based on the temporal and causal association of the disorder and its manifestation, e.g., nystagmus (disorder) is different from nystagmus present (finding). Nystagmus present (finding) may be a normal physiological response to head rotation. A person who spins around and has nystagmus present (finding), does not have nystagmus (disorder). Alternatively, a person may have nystagmus (disorder), but not nystagmus present (finding), i.e., they do not currently manifest nystagmus. Similarly, hearing loss (disorder) is different from perception of hearing loss (finding), which can be due to a number of temporary causes, such as excessive ear wax.
Pressure ulcer Pressure injury
|Pressure injury (disorder)| has been created in SNOMED CT based on the recommendations of the National Pressure Injury Advisory Panel (NPIAP) and adopted for the 2019 International Clinical Practice Guidelines on Prevention and Treatment of Pressure Ulcers/Injuries. The NPIAP nomenclature favors the use of pressure injury over pressure ulcer , due to confusion around the use of ulcer for two of the pressure ulcer stages which actually occur in intact skin.
New morphologies with text definitions have been created representing the various pressure injury stages:
|Damage (morphologic abnormality)|
|Pressure injury (morphologic abnormality)|
|Pressure injury stage I (morphologic abnormality)|
|Pressure injury stage II (morphologic abnormality)|
|Pressure injury stage III (morphologic abnormality)|
|Pressure injury stage IV (morphologic abnormality)|
1163215007 |Pressure injury (disorder)|and its descendants representing the pressure injury stages are defined with the morphologies above, similar to how burn injuries have been modeled in SNOMED CT.
Pressure injury morphology stages II - V have been assigned an additional parent of 56208002 |Ulcer (morphologic abnormality) |
Pressure injury morphology stage I has been assigned an additional parent of 70819003 |Erythema (morphologic abnormality) |
Pressure injury disorder concepts representing stages II - IV have a synonym of Pressure ulcer stage x
The following concepts have been inactivated and replaced with corresponding Pressure injury concepts:
421076008 |Pressure ulcer stage 1 (disorder)|
420324007 |Pressure ulcer stage 2 (disorder)|
421927004 |Pressure ulcer stage 3 (disorder)|
420597008 |Pressure ulcer stage 4 (disorder)|
723071003 |Pressure injury of deep tissue (disorder)| has previously been created but has been remodeled according to the above heuristics.
399912005 |Pressure ulcer (disorder)| has been inactivated and the remaining 33 descendants that do not mention a specific stage have been renamed using Pressure injury instead of pressure ulcer with the value of associated morphology value changed from 420226006 |Pressure ulcer (morphologic abnormality)| to 1163214006 |Pressure injury (morphologic abnormality)|. This results in these concepts being relocated under |Pressure injury (disorder)|.
Infectious vs. inflammatory
Disorders with the suffix "-itis" (e.g., cystitis, prostatitis, tonsillitis, appendicitis) are often infectious as well as inflammatory in nature.
For inflammatory conditions whose FSNs specify an infectivecause , the modeling should include:
|Causative agent (attribute)| with the specified organism
|Pathological process (attribute)| with the type of infectious process
|Associated morphology (attribute)| with Inflammatory morphology or subtype
|Finding site (attribute)| with a body structure when known
For inflammatory conditions whose FSNs do not specify an infective cause, an infectious cause should neither be assumed nor modeled when the FSN does not specify it. The modeling would then exclude a Causative agent and Pathological process and should include only:
|Associated morphology (attribute)| of Inflammatory morphology or subtype
|Finding site (attribute)| with a body structure when known
Example of inflammatory and infectious disorder,
441551009 |Inflammation of larynx caused by virus (disorder)| (synonym, Viral laryngitis) includes a |Causative agent (attribute)| of |Virus (organism)| and a |Pathological process (attribute)| of |Infectious process (qualifier value)|.
Example of inflammatory disorder not specified as infectious,
446292002 |Necrotizing inflammation of lymph node (disorder)| (synonym, Necrotizing lymphadenitis) does not specify an infective cause, so it is neither modeled with Causative agent nor Pathological process. The model contains an |Associated morphology (attribute)| and a |Finding site (attribute)|.
Pneumonia vs. Pneumonitis
The terms pneumonia and pneumonitis are often used interchangeably. In SNOMED CT, pneumonia is used for infectious causes, and pneumonitis is used for noninfectious causes.
Some concepts may contain a synonym with the other pneumoni- term due to high/common usage in medical literature.
Pneumonia is a type of pneumonitis, as inflammation is present in both. The distinguishing feature between the two disorders is the presence of infection in pneumonia. Pneumonia has a Pathological process (attribute) of Infectious process (qualifier value); pneumonitis does not.
Figure: Stated view of 205237003 |Pneumonitis (disorder)|
Figure: Stated view of 233604007 |Pneumonia (disorder)|
Morphologic abnormality
The morphologic abnormality for both 233604007 |Pneumonia (disorder)| and 205237003 |Pneumonitis (disorder)| is 409774005 |Inflammatory morphology (morphologic abnormality)|.
The clinically-warranted morphologic abnormality for many subtypes of pneumonia is 707496003 |Inflammation and consolidation (morphologic abnormality)|. Consolidation is a feature of most forms of pneumonia; however, it may not be a feature of all pneumonias, such as atypical pneumonias.
Guidance exception
Content has been added that aligns with the 2025 International Multidisciplinary Classification of the Interstitial Pneumonias with attribution to ERS/ATS - European Respiratory Society/American Thoracic Society. For these concepts, the fully specified term and preferred term align with the classification which uses the term pneumonia instead of pneumonitis, even in the absence of an infectious cause.
Body parts and regions
SNOMED CT uses the Foundation Model of Anatomy (FMA) definition of body part and body part subdivision for some concepts. For example, the joint regions discussed below are classified as body part subdivisions, since that is what is intended by the diseases and procedures that use these terms in their definitions. They are not body parts because they are defined, not by a set of bones, but rather by a particular joint and its surrounding structures. However, our interpretation of the word region is based on common usage and is intended as a three-dimensional structure, not the FMA two-dimensional definition of body region. In other words, these regions are not simply surface regions (skin), but also include the three dimensional underlying structures (subcutaneous tissues, bones, muscles, tendons, fascia, vessels and etc.).
Many concepts contain the phrase surface region. These could be interpreted as massless (immaterial) mathematical surfaces, but a clinical terminology would have no direct use for such meanings in clinical records. They could be interpreted as having mass (not immaterial), but the depth then is arbitrary. Should it be just skin deep, or should it include deeper layers of the surface? If only skin deep, the meaning of these concepts would overlap with concepts for skin regions. If deeper, the meaning would possibly be the same as the generic structure concepts.
The named regions of the abdomen are by tradition divided horizontally by the transpyloric plane and the interspinous plane, and vertically by the midclavicular plane. The lateral regions are therefore bounded above by a plane that is inferior to the ribs. In contrast, the flank is the lateral region of the abdomen bounded above by the ribs. Thus some parts of the hypochondriac regions, which are superior to the transpyloric plane but inferior to the ribs, would be considered also part of the flank. The hypogastric region is also sometimes called the pubic region.
Specific Clinical finding and Disorder Modeling
Observable Entity
Definition
Examples
Observables entities may be used to code headers on a template, elements on a checklist, or to assign values to elements.
Congenital
Second toe structure (body structure)
Second toe structure
Second digit of foot
Second toe
Third toe structure (body structure)
Third toe structure
Third digit of foot
Third toe
Fourth toe structure (body structure)
Fourth toe structure
Fourth digit of foot
Fourth toe
Little toe structure (body structure)
Little toe structure
Fifth digit of foot
Fifth toe
is a neural tree organ, so there is no need for an additional concept called
facial nerve and its branches
.
Entire cranial nerve is a neural tree organ and structure of cranial nerve is that organ or any part (or branch) thereof. Branches of the cranial and spinal nerves are segments of the neural tree organs from which they branch.
All concepts named nerve x and its branches were inactivated due to their ambiguity. There are MAY BE A links to structure of nerve x , and entire nerve x. Specifying trunk of a nerve requires a specific concept.
-Necessarily have an underlying pathological process
-Have temporal persistence (may be under treatment, in remission, or inactive, even though they are still present)
-May be present as a propensity for certain abnormal states to occur, even when treatment mitigates or resolves those abnormal states
Finding
-May be normal (but not necessarily)
-May exist only at a single point in time (e.g. a serum sodium level)
-Cannot be temporally separate from the observation (one cannot observe them and say they are absent, nor can they be present when they cannot be observed)
-Cannot be defined only in terms of an underlying pathological process that is present, when the observation itself is not present
The NPIAP classification best supports the disambiguation of pressure ulcer from intact skin lesions. The SNOMED CT pressure injury disorder hierarchy follows the NPIAP terminology most closely but accommodates legacy classifications by including an ulcer morphology in the model as well as additional descriptions of pressure ulcer for pressure injury stages II - VI.
|Color of nail| is an observable entity. |Gray nails| is a finding.
There are four general types of observable entities for use in health care. Each has different representation requirements and patterns, i.e. the set of attributes will vary.
Quality. A characteristic, feature, or property that is inherent in someone or something.
For example, mass of a person, temperature of internal organs, concentration of sodium in plasma, angle of a joint
Disposition. A characteristic or feature that is not always realized in full.
For example, antibiotic susceptibility of a certain population
Function. The ability of a person, some part of a person, or a thing to perform activities or realize processes.
For example, ability to walk
Process. A process or outcome of a process
For example, secretion rate, heart rate, respiratory rate
The observable entity and evaluation procedure hierarchies have some of the same attributes. While there should not be a one-to-one correspondence between concepts in these hierarchies, legacy implementations, as described below, may result in the occasional duplication of content.
SNOMED CT contains some concepts in the evaluation procedure hierarchy that logically belong in the observable entity hierarchy. This is a legacy issue that has been discussed extensively with the community of practice without resolution. At this time, the existing evaluation procedure hierarchy will be retained to support existing use cases. No new laboratory content under 122869004 |Measurement procedure (procedure)| will be added in the international release, as this domain is comprehensively covered by the LOINC extension to SNOMED CT. New laboratory content needed to satisfy existing use cases should be sourced from that extension. For non-laboratory content in the evaluation procedure hierarchy — such as clinical measurements performed directly on a patient rather than on a patient sample — new concepts may continue to be added where needed, although it is preferred that they be represented as observable entities.
While some users have indicated they require the use of a measurement procedure concept for ordering and an observable entity concept for reporting the result, this is not the preferred approach for the international release of SNOMED CT nor is it in line with other terminology standards such as LOINC and NPU. When a laboratory or clinical measurement procedure is ordered, there is an expectation that a value will be provided in association with that order. In these cases, measurement procedures are, for all intents and purposes, observables with a different semantic tag. The nature of their top-level parent (122869004 |Measurement procedure (procedure)|) implies that they require a value in order to be assessed and are therefore equivalent to observables.
As for the progression of the completion of an assessment, that is related to the state diagram (i.e., status) of the progression of a procedure and should not be precoordinated, but handled by the information system in which orders are processed (it is dynamic, not static). The information system should be able to capture the status of a procedure (e.g., ordered, in process, completed). We would not expect the terminology to pre-coordinate this.
For example, LOINC recognizes three different aspects to an observable:
those that can serve as both an order and an observation (e.g. blood glucose level);
those that can be ordered but not directly resulted (e.g. urinalysis, which is a convenience order for multiple individual observations on urine); and
those that can only be resulted and not directly ordered (usually part of an automated system, such as computation of MCHC in hematology).
LOINC assigns this aspect with an attribute value. It is not one of the six main LOINC parts typically visible to users; however, it is included in the LOINC database.
Information about a quality/property to be observed and how it will be observed
416320009 |Calcium volume (observable entity)|
276885007 |Core body temperature (observable entity)|
Use of Observable Entities
Types of Observable Entities
Observable Entity vs. Evaluation Procedure
Because both observable entities and evaluation procedures may be used for ordering, any analytics derived from order data must account for both hierarchy types to ensure complete and accurate results.
Some areas of the observable entity hierarchy need clarification and remodeling. This includes upper level concepts and hierarchies such as 246464006 | Function (observable entity) | and 415178003 | Process (observable entity) | as well as intermediate primitive and leaf node concepts.
The term abdominal cavity has two meanings, one including the pelvic cavity , the other excluding it. Abdominal cavity structure includes both. Abdominal cavity proper excludes the pelvic cavity.
The FMA definition of body organ is also used. Organs include individual bones, joints, muscles, arteries, veins, lymph vessels, nerves, and etc. Concepts that include groups of organs are frequently used in SNOMED CT. In most cases, these have been part of the subsumption hierarchy (IS A hierarchy) of the particular organ type, that is, they are kinds of organs.
For concepts that refer to the collection of organs (rather than organs in a collection), there is another concept that is a, kind of, organ system subdivision. Many such collections do not yet have corresponding organ system subdivision concepts. The default is to interpret concepts as denoting organs, rather than organ system subdivisions.
Organ
Organ system subdivision
Vertebra (bone of vertebral column)
Spine (subdivision of skeletal system)
Cervical vertebra
Cervical spine (subdivision of spine)
Third cervical vertebra
In general, organs are made up of tissue, and tissue is made up of cells. However, a cell is not necessarily part of tissue, and tissue is not necessarily part of a named organ.
Arteries, veins, nerves, and the bronchi form tree-like structures that distribute across multiple regions. Because of their size and links with other structures, they require slightly different modeling. FMA divides tree structured organs as: organs with organ cavities and organs that are solid.
Organ with organ cavity has a subtype, hollow tree organ. The hollow tree organs are:
Tracheobronchial
Biliary
Vascular
Arterial
Systemic arterial
Pulmonary arterial
Venous
Systemic venous (superior, inferior, and 4 cardiac trees)
Pulmonary venous (superior and inferior left and superior and inferior right)
Portal venous
Lymphatic (right lymphatic duct and thoracic duct)
Among the solid organs, there is one category, neural , that is tree-structured (see: Nervous system; neural tree).
Male and female are unnecessary descriptions in describing the breast. Gender information should be obtained and recorded separately in the information model. New content that requests male or female breast will not be accepted so as not to duplicate gender-specific anatomical concepts.
Most surface region concepts will be retired as ambiguous/_possibly equivalent to _their corresponding concepts that are clearly not immaterial, including x structure, entire x, and skin of X. Where the x structure codes do not currently exist, they will be created, without the surface region phrase.
Abdominal regions
Abdominal cavity, pelvic cavity
Organs, organ system subdivisions
Collections of Organs with/without Organ System Subdivisions
Unacceptable terms
X disorder at Y level concepts originating from ICD-11, e.g., Skin laceration of arm at wrist level (precedent are terms added from ICD-9) are not added to the SNOMED International Release.
Cell, tissue, organ
Tree structured organs
Hollow tree organs
Breast
Laterality
For information on laterality, see Anatomical Structure Naming Conventions section at and Laterality section at
Determine if an anatomy structure is lateralizable
The anatomy structures should only be pre-coordinated with laterality if they are lateralizable. All anatomy structures on the midline are not lateralizable. The Lateralizable Body Structure Reference Set has been developed and published as part of SNOMED International release. Please note that the refset requires an ongoing update for new additions.
In this guide, the lateralizable anatomy structures are divided into three types:
X
The type X represents any anatomy structure that is lateral to mid-sagittal plane.
Creation of lateralized anatomy structure
Both Left and Right structures must be added when adding the new pre-coordinated concepts for anatomy structure with laterality. Lateralization should not be routinely applied to Entire and Part of anatomy concepts unless the concept model requires such lateralized anatomy structure.
Bilateral X anatomical structure (body structure) must not be added. The concepts under 422525002 |Structure of bilateral paired structures (body structure)| are no longer in use in the international edition of SNOMED CT because bilateral concepts are defined by two role groups. However, these concepts may still be in use by extensions, in post-coordinations, or as values in information models. We would recommend users to review their usage and provide feedback to us. Users will be consulted before these concepts are ultimately inactivated.
Term patterns for laterality
Following are the most common term patterns for the representation of laterality for anatomy structures. Preferred terms should have the same description without a semantic tag. In descriptions in hierarchies such as clinical finding/disorder, procedure, observable entity, and situation with explicit context, 'structure of' can be omitted when body site is not a concept of Entire anatomy entity.
Structure of + left/right + X or Structure of + left/right + half of Y
Structure of left hand (body structure)
Structure of right lung (body structure)
Structure of left ring finger (body structure)
Structure of left renal artery (body structure)
Bone structure of left tibia (body structure)
Structure of right half of head (body structure)
Structure of right cerebral hemisphere (body structure)
Bone structure of left hand (body structure) - bone structure is constitutional part of hand
Bone structure of phalanx of left ring finger (body structure)
Skin structure of right foot (body structure) - skin structure is constitutional part of foot
Skin structure of left index finger (body structure)
Finger/toe is not sufficient - Laterality should be placed before hand/foot when finger/toe or any part of a finger/toe is not further specified to individual digit, e.g., ring finger, index finger, great toe.
Example
Evalution
Parts of symmetric structures should be symmetric. However, some body parts are exceptions. The laterality value in modeling is inherited from its lateralizable parent concept, e.g. left/right lung structure. Therefore, descriptions must clearly indicate such inheritances to avoid potential confusion. It is not accurate for a term such as "right middle lobe" because there is no "left middle lobe". The following are examples for correct description pattern. Note: existing content has not been following the term pattern.
Leave the new concept as primitive if concept 'Structure of half of Y lateral to mid-sagittal plane (body structure)' does not exist. The new concept for 'Structure of half of Y lateral to midsagittal plane' should not be added until the policy is developed.
The 'part of' relationship should not be used for concept modeling in anatomy. The laterality attribute should be the only attribute for the representation of laterality. The new concept model for anatomy has not been implemented, and the proximal primitive modeling style should not be applied.
For term pattern 1, the concept X or lateral half of Y should be used to fully define a concept with laterality, as shown in these examples:
For term pattern 2, the pre-coordinated concept {part} of X should be used to fully define the concept with laterality. Note: Concepts for which an identifier has not been assigned have been shown with an identifier of '1111111111'.
For example,
Please note that the concept modeling and utility of pre-coordinated concepts of 'structure of {part} of lateral half of Y' and 'structure of half of Y lateral to mid-sagittal plane' are still under investigation. Similar new anatomy concepts should not be added. The concept model should only use existing pre-coordinated concept {part} of lateral half of Y.
For example,
If pre-coordinated concept does not exist for '{part} of structure of half of Y' or 'structure of half of Y lateral to mid-sagittal plane', the concept can be defined by {part} of Y and the definition status should be primitive.
For example, concept |Structure of lateral half of lower back| does not exist, the concept 'Structure of left half of lower back' should be defined as a primitive concept. Two parent concepts are expected: 61379005 |Structure of left side of trunk (body structure)| and 37822005 |Lower back structure (body structure)|. The additional parent |Structure of left side of trunk (body structure)| is to ensure that any lateralized concept must be a subconcept of a lateralizable structure.
Cardiovascular System
Cardiac valves, normal and malformed
There are a number of concepts in the anatomy hierarchy that represent congenital cardiac malformations. This content was developed in cooperation with IPCCC (International Pediatric and Congenital Cardiac Code).
The following pairs of cardiac valve concepts do not represent the same thing and are siblings, not super- or subtypes, to each other:
46030003 |Tricuspid valve structure (body structure)| vs. 244344000 |Entire right (non-tricuspid) atrioventricular valve (body structure)|
Atrioventricular (non-mitral, non-tricuspid) valves represent body structures which were anatomically abnormal from the beginning of their development. They are not called mitral/tricuspid valve although they perform the same function as their normal counterpart would. They are also represented using the term not morphologically mitral/tricuspid valve.
For example,
459176007 |Abscess of right atrioventricular (not morphologically tricuspid) valve (disorder)| represents an abscess of the right atrioventricular valve that has been developed abnormally from the beginning vs. 431189009 |Abscess of tricuspid valve (disorder)|.
For a normally developed mitral/tricuspid valve, the term left/right atrioventricular valve can be used interchangeably. They are true synonyms. However, they cannot be used for abnormally developed valves, i.e. left atrioventricular (non-mitral)/right atrioventricular (non-tricuspid) valves.
The systemic circulatory system is the combined arterial and venous circulation that begins where blood leaves the left ventricle and ends where blood enters the right atrium. It excludes the coronary circulation. The heart chambers are also considered part of the circulatory system.
The pulmonary circulation is the combined arterial and venous circulation that begins where blood leaves the right ventricle and ends where blood enters the left atrium.
Any artery of the pulmonary circulation, i.e. arteries carrying unoxygenated blood from the heart to the lungs. They include the trunk, right and left branches of the pulmonary artery (which are within the mediastinum), and all of their branches (which tend to occur at or past the hilum and are therefore regionally within the lung).
Any artery of the pulmonary circulation that is regionally within the lung, the boundary being defined by the hilum.
The main pulmonary artery (one of the great vessels that enter the heart) carrying blood from the right ventricle and dividing into right and left main pulmonary arteries (some dictionaries consider this synonymous with pulmonary artery).
There are four pulmonary veins that enter the left atrium, two on each side. These are what is intended by the name pulmonary vein (great vessels that enter the heart). In common usage, any vein that is part of the lung may be referred to as a pulmonary vein, but SNOMED CT has a separate concept: 122972007 |Pulmonary venous structure (body structure)|. This means any vein that drains the lung. A synonym is vein of lung. Pulmonary veins are veins of the lung, but pulmonary vein and vein of lung are not synonyms.
The term central vascular is not in common use. In fact, the term does not appear in SNOMED CT. However, the term peripheral vascular is very common, and therefore it requires a definition that (by default) sets the boundary between central and peripheral vascular systems.
The simplest definition of the peripheral vascular system is the vascular system that is not central; and then the central vascular system includes the pulmonary circulation, coronary circulation, cerebrovascular system, thoracic aorta, superior vena cava, inferior vena cava, and mediastinal blood vessels.
Peripheral vascular disease is often distinguished from cerebrovascular disease and coronary artery disease. These are the three major categories of diseases caused by problems in vascular circulation in general, and atherosclerosis, in particular. As a result of this clinical distinction, the cerebrovascular system is excluded from the peripheral vascular system.
Cerebrovascular is commonly defined in two ways: the blood vessels in the brain, or the blood vessels that supply the brain (including those within the brain). Because cerebrovascular disease includes extra-cranial occlusions of the vertebral and carotid arteries, we define the cerebrovascular system as those vessels involved in the supply and drainage of blood to the brain. Convention does, however, tend to exclude the innominate artery - which gives rise to the right common carotid and the arch of the aorta which gives rise to the left common carotid. Convention also excludes the subclavian arteries which give rise to the vertebral arteries.
The common carotid artery has a left and right component. The right common carotid artery has no thoracic portion (it arises from the brachiocephalic trunk behind the right sternoclavicular joint). The left common carotid artery has a thoracic portion (It arises from the arch of the aorta). Thus, the common carotid artery (not specifying laterality) is not exclusively an artery of the neck. This is because of the thoracic portion of the left common carotid artery. Then, artery of neck region includes the cervical part of left common carotid artery and all of the right common carotid artery.
Some vascular trees are located wholly within the cranial cavity, but some (internal carotid; vertebral) cross the boundary between extra- and intra-cranial. Intracranial segments of such vascular trees must be individually identified as such, and the entire vascular tree must not be categorized as either extra- or intra-cranial.
The word artery has three different meanings. In modeling SNOMED CT concepts that refer to arteries, it is necessary to decide on a case-by-case basis which of these meanings is intended.
Meanings
Notes
Examples
The word vein has three different meanings. In modeling SNOMED CT concepts that refer to veins, it is necessary to decide on a case-by-case basis which of these meanings is intended.
Meaning
Notes
Because trunks of veins, not venous trees, have been used to organize the vein hierarchy, there are implications for regional classes.
For example, the internal jugular vein is a vein of the neck, but its entire venous tree extends into the head. The internal jugular vein venous tree is not strictly part of the neck, even though the internal jugular vein venous trunk is strictly part of the neck.
Tributaries are also modeled as direct tributaries of the trunk. A tributary of a named vein is part of the venous tree of the named vein, but not part of the venous trunk of the named vein. Some veins that are part of the venous tree , and therefore might be regarded as indirect tributaries, are not modeled as direct tributaries of the trunk of the vein. Direct tributary is the intended meaning of tributary.
Anatomy relating to the spine
The terms 'spine' and 'vertebral column' in descriptions of conditions or procedures are often used loosely in clinical discourse but can relate to three different general anatomical concepts:
includes the bones of the spine and associated joints and ligaments
289959001 |Musculoskeletal structure of spine (body structure)|
includes the vertebral column plus muscles and tendons associated with the spine
1141981001 |Structure of vertebral column region (body structure)|
includes the musculoskeletal structure of spine plus spinal canal, meninges, spinal cord, roots and ganglia and immediate soft tissue including adjacent vascular structures where specified.
The last concept has been allocated the following definition: This volume includes the spinal column, its spaces and contents, notably the spinal canal, spinal meninges and spinal cord. It also includes the muscles associated with the spine within (and including) the anterior and posterior thoracolumbar fascia and its equivalent nuchal fascia in the neck. This region also includes the spinal ventral (anterior) and dorsal (posterior) roots, the dorsal root (spinal) ganglions and the spinal nerve trunks.
To emphasize the different volumes, cross-sections are shown below of (Figure 1) the vertebral column in yellow, and (Figure 2) the larger vertebral column region in amber color.
From the preceding descriptions, it is clear that Vertebral column region is a broader concept for 'spine', and it should be used when a procedure or condition could involve not only the bony component of the vertebral column, but also the spinal cord, nerve root, muscle, bone, or joint of spine.
For example,
MRI of thoracic spine (procedure) is modeled with 1141986006 |Structure of thoracic vertebral column region (body structure)|.
Pain in sacrum (finding) is interpreted as being related to the more general notion of 1144746008 |Structure of sacral vertebral column region (body structure)|.
When a procedure or disorder is exclusively related to musculoskeletal structures of the spine, the 'musculoskeletal structure of spine' should be used.
For example,
Cervical traction (procedure), Manipulation of the cervical spine (procedure), and Rotational deformity of cervical spine (finding) are all modeled with 297166009 |Structure of musculoskeletal system of cervical spine (body structure)|.
Where a procedure or condition only effects the bone, joint, or ligament component (and not the muscles or tendons directly) the ‘vertebral column variant’ is used for modeling.
For example,
Benign neoplasm of lumbar vertebral column (disorder) and Kyphoplasty of fracture of lumbar spine using fluoroscopic guidance (procedure) are both modeled with 122496007 |Structure of lumbar vertebral column (body structure)|.
The sacrum is considered equivalent to the sacral vertebral column, as it is composed of the bone structure of the sacrum plus the joint structure of sacrococcygeal junction of spine.
The spine is traditionally divided into the following regions:
Cervical
Thoracic
Lumbar
Sacral
The anatomy of these individual segments are structured in accordance with the description above.
The regions and joints between these identified segments are referred to as cervicothoracic, thoracolumbar, lumbosacral and sacrococcygeal. The meaning of these words are subject in common parlance and some literature to be ambiguous.
For example,
‘Thoracolumbar’ sometimes refers to the thoracic spine and lumbar spine, or alternatively, it is used to express the junction between the thoracic spine and lumbar spine.
To avoid false assumptions, the junction of spinal segments in SNOMED CT have been made explicit by including the word junction in descriptions. This avoids potential misinterpretation as to whether a word such as ‘thoracolumbar' relates to both spinal segments or just the adjacent volume.
For example,
The notion of 1145014005 |Structure of thoracolumbar junction of vertebral column (body structure)| is only used for modeling when it is explicitly stated in the target concept e.g. 281907005 |Fracture dislocation of thoracolumbar junction (disorder)|.
By contrast, in the circumstance where a dependent concept relates to the combination of two segments, e.g. 702487007 |CT of thoracolumbar spine (procedure), (FSN Computed tomography of thoracic and lumbar spine), the concept is modeled with two axioms, namely Structure of lumbar vertebral column region and Structure of thoracic vertebral column region.
The volume or extent of the junctional zones themselves are not defined consistently in the literature but most commonly relate to the junction between two segments and one vertebra above and below. So the convention used in the SNOMED CT anatomy hierarchy follows this guidance.
For example,
1145014005 |Structure of thoracolumbar junction of vertebral column (body structure)| includes the following concepts in its class:
66794005 |Bone structure of L1 (body structure)|
23215003 |Bone structure of T12 (body structure)|
714833001 |Structure of intervertebral syndesmosis of T12 and L1 (body structure)|
181879009 |T12/L1 facet joint (body structure)|
In addition, a further convention is required as to where segmental junctional joints belong, i.e. either to the cephalic or caudal segment. For instance, does the T12/L1 facet joint relate to the Thoracic spine joint structure or/and Lumbar spine joint structure?
The convention used (based on common criteria of spinal injuries) is that the junctional joints are included with the cephalic segment. So, in the case of the T12/L1 facet joint, it is included in the class of Thoracic spine joint structure (body structure).
See also Anatomical Structure Naming Conventions section and Laterality section
Right, left disorder concepts
When creating a lateralized disorder concept, two concepts should be created:
concept for the left side
concept for the right side
Descriptions
FSN: <morphologic abnormality> of <right/left> <body structure> (disorder)
PT: Right/left
For example, 1089071000119109 |Inflammation of left mastoid (disorder)|
FSN: Inflammation of left mastoid (disorder)
PT: Left mastoiditis
When creating a lateralized disorder concept, if a non-lateralized parent does not exist, then it should be created as well. In other words, do not just create the right and left versions, but also create a concept to represent the laterality-agnostic parent.
For example,
When creating Inflammation of left mastoid and Inflammation of right mastoid, also ensure a concept for Inflammation of mastoid exists.
Where the disorder is left/right of a specific anatomical site, and the preferred term naming pattern of Right/left causes a combination that does not sound like natural flowing English, the guidance above can be circumvented. See the section and Laterality section .
For example,
Left interphalangeal thumb joint open traumatic dislocation should follow naming guidance of Open traumatic dislocation of interphalangeal joint of left thumb.
Left abscess of foot is an incorrect term; instead, this should read Abscess of left foot.
Where the bilateral disorder description causes a combination that does not sound like natural flowing English, the guidance below can be circumvented.
FSN: of bilateral (disorder)
PT: Bilateral
SYN: of bilateral
SYN: of both
FSN: of bilateral (disorder)
PT: of bilateral
SYN: of both
Note the PT of Bilateral is not required. Bilateral is to describe the body site, not the morphologic abnormality.
For example, 15725081000119100 | Effusion of joint of bilateral feet (disorder) |
FSN: Effusion of joint of bilateral feet (disorder)
PT: Effusion of joint of bilateral feet
SYN: Effusion of joint of both feet
Also note that joint is singular. This is to denote that the joint may be singular on each side of the body; the plurality of feet will represent the laterality. Using joints as plural may incorrectly reflect that there are multiple joints affected in both feet.
Bilateral disorders should be modeled using two relationship groups, one for each lateralized body structure.
Immune function disorders
Hypersensitivity
473010000 |Hypersensitivity condition (finding)| is a primitive concept. It subsumes 473011001 |Allergic condition (finding)| and 609405001 |Non-allergic hypersensitivity condition (finding)|.
473010000 |Hypersensitivity condition (finding)| is a direct descendant of 404684003 |Clinical finding (finding)|.
473011001 |Allergic condition (finding)| and 609405001 |Non-allergic hypersensitivity condition (finding)| are both primitive concepts. Each has three main subhierarchies representing:
Diseases/disorders: abnormal structures
Processes: allergic and nonallergic hypersensitivity (pseudoallergic) reactions
Dispositions: propensities to develop allergic and nonallergic hypersensitivity (pseudoallergic) reactions; they do not have pathophysiologic manifestations prior to allergic and nonallergic hypersensitivity (pseudoallergic) processes, i.e. reactions
Diseases/disorders and reactions, but not dispositions, are defined by underlying pathological processes.
Allergic reaction (disorder) has a Causative agent (attribute) of Substance (substance) or its subtypes. This attribute-value pair is grouped with another attribute-value pair of Pathological process (attribute) and Allergic process (qualifier value).
Allergic process (qualifier value) is a subtype of Abnormal immune process (qualifier value) which means allergic disorders, as well as autoimmune disorders, classify as types of disorders of immune function. Disorder of immune function (disorder) modeling with Abnormal immune process (qualifier value) allows allergic and autoimmune disorders to correctly classify as subtypes of Disorder of immune function (disorder).
Allergic and nonallergic hypersensitivity (pseudoallergic) diseases represent manifestations of pathologic processes that result in abnormal structures. Modeling an allergic and nonallergic hypersensitivity (pseudoallergic) disease includes the following relationship group:
IS A: Disease (disorder)
Associated morphology (attribute): subtype of Morphologically abnormal structure (morphologic abnormality) representing the abnormal structure
Finding site (attribute): subtype of Anatomical or acquired body structure (body structure) representing the abnormal structure
Pathological process: Hypersensitivity process (qualifier value) or one of its descendants
For example,
Allergic and nonallergic hypersensitivity (pseudoallergic) dispositions are propensities to develop allergic and nonallergic hypersensitivity (pseudoallergic) reactions; they do not have pathophysiologic manifestations prior to reactions. They are considered clinical findings, not disorders. This further distinguishes them from allergic and nonallergic hypersensitivity (pseudoallergic) reactions.
Allergy to X (finding) will have the following modeling:
IS A: Propensity to adverse reaction (finding)
Role group of:
Has realization (attribute): Allergic process (qualifier value)
Causative agent (attribute): subtype of Substance (substance)
For example,
For example,
Nonallergic hypersensitivity (pseudoallergic) reactions are adverse reactions; they are defined by an underlying pathological process.
For example,
Figure: Example of nonallergic hypersensitivity (pseudoallergic) reaction model in stated view
An intolerance is the propensity to develop an adverse reaction to a substance. The adverse reaction may be associated with various pathological processes, but specifically excludes hypersensitivity reactions.
It may be difficult to define the pathological process and to associate the substance with the propensity to develop a reaction. Consequently, 47429007 |Associated with (attribute)| is used to model intolerance to substances.
For example,
Complication and Sequela Modeling
Combined disorders can occur, for example:
One disorder causes the other (causal relationship)
One disorder is temporally related to another
Two disorders have both a causal and temporal relationship to each other
Attributes that can be used to define such causal and temporal relationships are:
Associated with (attribute)
Causative agent (attribute)
Due to (attribute)
Temporally related to (attribute)
A complication is an unexpected condition, outcome, or adverse event due to another condition, procedure, or treatment.
Concepts representing a disorder caused by another disorder, or disorders following either medical or surgical procedures should be modeled using a parent of 64572001 |Disease (disorder)| or the appropriate intermediate primitive. The word complication in an FSN should only be used when it can be verified that the caused disorder is an unintended or unexpected event.
Conditions that are caused by another condition, but are not unexpected, should be modeled with a DUE TO relationship, but should not be named as complications.
For example, 10629511000119102 |Rhinitis of pregnancy (disorder)|
Conditions co-occurrent with another disorder but are not caused by the underlying disorder are co-morbidities and should not be modeled using the DUE TO relationship.
For example, 31563000 |Asymptomatic bacteriuria in pregnancy (finding)|
Perioperative complications refer to complications temporally related to a surgical procedure. They include pre-operative, intra-operative and post-operative complications and are modeled with a parent of Disease (disorder) and a relationship consisting of Temporally related to (attribute) or an appropriate subtype with a value of <<387713003 |Surgical procedure (procedure)|. A temporal complication does not necessarily imply a causal (Due to) relationship to the surgery itself, as the complication may be related to any disorder, event, or procedure occurring either prior, during, and/or after surgery. For this reason, perioperative complications do not have a stated Due to relationship unless an underlying cause is clearly stated in the FSN.
The following naming convention applies to those conditions that occur temporally, i.e. either before, during, or after the operative episode but do not have a causal relationship.
FSN: Postoperative X (disorder)
PT: Postoperative X
For example,
Perioperative hematoma (disorder)
Postoperative hypothyroidism (disorder)
This attribute is used to model concepts in which a clinical finding occurs after another clinical finding, procedure, or event. Neither asserting nor excluding a causal relationship, it instead emphasizes a sequence of events. Naming pattern is ‘x following y’.
For example,
123948009 |Disorder following viral disease (disorder)| occurs After (attribute) 34014006 |Viral disease (disorder)|
The Due to and After attributes are used to model a disorder that occurs after a disorder or procedure with a causal relationship. Both the cause and the After relationship must be specified. The naming pattern is due to and following.
This attribute is used to model a preoperative complication. Strictly, a preoperative complication is a disorder that complicates the procedure, rather than being a complication of that procedure. A preoperative complication might be considered to be a disorder that exists prior to surgery that adversely affects the surgery or that results in an intraoperative or postoperative complication.
This attribute is used to model a disorder that occurs during a procedure.
For example,
Due to and During attributes can be used to model a disorder that occurs during a procedure (e.g., intraoperative complication) with a causal relationship. Both a cause and a temporal relationship to the cause must be specified.
A sequela is a disorder that is a consequence, but not an unexpected outcome, that follows after another disorder, procedure, or event. These conditions are often described with the words following, after, post,sequela(e), or late effects.
Sequelae can be in the following forms:
Following
Due to and following/after
During and following/after
These conditions should be modeled with After (and also Due to if there is a causal relationship).
For example,
Disorder due to and following another disorder = 698737005 |Obstructive hydrocephalus due to and following meningitis (disorder)|
FSN: Disorder X [due to and] following <<disorder /<<procedure /<event
PT: Disorder X [due to and] following <<disorder /<<procedure /<event
SYN: [Disorder X as a] Sequela of <<disorder /<<procedure /<event
SYN: [Disorder X as a] Late effect of <<disorder /<<procedure /<event
For example,
Disorder due to and following another disorder (disorder)
Disorder due to and following meningitis (disorder)
Disorder due to and following procedure (disorder)
Not all surgical sequelae are complications of surgery but rather expected late effects. Conditions that occur following surgery, but not necessarily Due to the surgery, are modeled only with an After relationship.
FSN: Disorder X following << 387713003 |Surgical procedure (procedure)
PT: Disorder X following << 387713003 |Surgical procedure (procedure)
For example,
Contraction of eye socket following enucleation (disorder)
Scar following surgery (disorder)
Conditions that occur following surgery and are explicitly stated as causal/due to are modeled with a Due to (attribute) of << 387713003 Surgical procedure, and an After (attribute) of << 387713003 Surgical procedure.
FSN: Disorder X due to and following <<387713003 |Surgical procedure (procedure)
PT: Disorder X due to and following <<387713003 |Surgical procedure (procedure)|
For example,
Encephalopathy due to and following cardiopulmonary bypass (disorder)
Cataract lens fragments in vitreous of eye due to and following cataract surgery (disorder)
Disorder due to and following breast reduction (disorder)
Event Attributes Summary
When authoring in this domain, these are the approved attributes and allowable ranges.
Domain Information for Event
Property
Value
Domain Constraint
<< 272379006 | Event (event) |
Parent Domain
Attribute
Grouped
Cardinality
In Group Cardinality
Range Constraint
Allergy to X vaccine
Overview
The following modeling and terming guidelines apply to concepts in the International Release.
Modeling
"Allergy to X vaccine" concepts shall be modeled using the proximal primitive modeling pattern. Due to the small number of concepts (n<25), no template will be created. The "Allergy to substance" template can be consulted for generalized modeling guidance.
Single or multiple ingredient vaccine
Stated parent concept
420134006 |Propensity to adverse reaction (finding)|
Semantic tag
The following illustrates the stated view for top level grouper 863903001 |Allergy to component of vaccine product (finding)|:
The following illustrates the inferred view for top level grouper 863903001 |Allergy to component of vaccine product (finding)|:
The following illustrates the stated view for 294663006 |Allergy to component of vaccine product containing Hepatitis A virus antigen (finding)|:
The following illustrates the inferred view for 294663006 |Allergy to component of of vaccine product containing Hepatitis A virus antigen (finding)|:
The following illustrates the stated view for 294662001 |Allergy to component of vaccine product containing Measles morbillivirus and Mumps orthorubulavirus and Rubella virus antigens (finding)|:
The following illustrates the inferred view for 294662001 |Allergy to component of vaccine product containing Measles morbillivirus and Mumps orthorubulavirus and Rubella virus antigens (finding)|:
Anatomical Concept Model
SNOMED CT uses a structure-entire-part triple, known as the SEP triple , to represent anatomical structures. The following Relationships provided a way for the anatomy in CTV3 to be mapped to RT:
The SNOMED CT anatomy hierarchy differentiates classes of entire anatomical entities from classes of parts of entire anatomical entities.
Entire concept : Denotes a class that is instantiated by entire anatomical entities of some kind: entire heart is instantiated by all individual hearts.
Entity Part concept: Denotes a class that is instantiated by all anatomical entities that are a proper part of some entity of a given kind: heart part is instantiated by all entities that are a proper part of some heart, e.g. my mitral valve, your right ventricle, Joe's sinus node. Heart part is not instantiated by any heart.
Entity Structure concept : Subsumes both the related Entire and Part concepts. Consequently, it denotes a class which is instantiated by anything that instantiates either the Entire or the Part. For instance, Heart structure is instantiated by my heart, my mitral valve, your heart, your right ventricle, Joe's sinus node, Joe's heart, etc.
Adverse reaction to X vaccine
The following modeling and terming guidelines apply to concepts in the International Release.
"Adverse reaction to X vaccine" concepts shall be modeled using the proximal primitive modeling pattern. Due to the small number of concepts (n<50), no template will be created. The "Adverse reaction to substance" template can be consulted for generalized modeling guidance.
Single or multiple ingredient vaccine
Maternal, fetal, neonatal
The life phase of pregnancy is unique in that two actors are participants in the scenario, and modeling must distinguish between the two.
For example,
Fetal tachycardia in antepartum versus Maternal tachycardia in antepartum
Mother and fetus share many time periods, such as antenatal. However, some periods are not shared, as in the case of intrapartum. The mother’s intrapartum period includes stages one, two, and three; the fetus’ intrapartum period includes only stages one and two.
A diagram of the relationships between these periods is shown below:
Observable Entity and Microbiology Test Results
When microbiology laboratory results are encoded, it is important to be aware of the context provided by the observation, i.e. the test performed and, therefore, the implied meaning of the result value, i.e. the organism.
For example, the combination of Logical Observation Identifiers Names and Codes (LOINC) for the lab test and SNOMED CT for the organism, provides a unique and specific meaning:
LOINC provides microbiology reporting codes with attributes including the property through the use of PRID(presence or identity) and the scale through the use of NOM (nominal or categorical response that does not have a natural ordering) as the result value (typically the name of organism).
Congenital
The concept 66091009 |Congenital disease (disorder)|, means present at birth. Though the word congenital may be applied to genetic disorders, the term genetic is preferred for those disorders.
The logical definition of a congenital disorder must include:
For example, 1084011000119100 |Inflammation of bilateral mastoids (disorder)|
FSN: Inflammation of bilateral mastoids (disorder)
PT: Bilateral mastoiditis
SYN: Inflammation of bilateral mastoids
SYN: Inflammation of both mastoids
Unilateral
With the addition of lateralized content in the International Release, the need for unspecified unilateral concepts is removed, as well as potentially dangerous, if used directly in a patient record. Unilateral concepts are not accepted.
Bilateral disorder concepts
When the body structure and the morphologic abnormality are combined into one word, the following naming pattern applies:
When the body structure and morphologic abnormality are separate, the following naming pattern applies:
Do not use both to describe disorders of the eyelids unless the concept means both upper eyelids or both lower eyelids; only then can that synonym be included for bilateral eyelid disorder concepts.
Modeling of bilateral disorders
Structure, Structure of
Lateralized disorder concepts should not include the words structure or structure of.
For example,
With use of 266005 |Structure of lower lobe of right lung (body structure)|:
a disorder concept is termed |Malignant neoplasm of lower lobe of right lung (disorder)|
a procedure is termed |Lobectomy of lower lobe of right lung (procedure)|
Stated view of Inflammation of left mastoid (disorder)
Stated view of Inflammation of bilateral mastoids (disorder) with a role group for each side
Before (attribute)
During (attribute)
After (attribute)
Complication
Perioperative complications
88797001 |Complication of surgical procedure (disorder)| is not a subtype of perioperative complication, as it does not include a temporal relationship. Similarly, 738668004 |Perioperative complication (disorder)| is not a subtype of 88797001 |Complication of surgical procedure (disorder)|, as there is no causal relationship. Some disorders may specify both a causal and temporarily relationship and would be modeled such that they would classify under both 738668004 |Perioperative complication (disorder)| and 88797001 |Complication of surgical procedure (disorder)|.
The following attributes are used in the modeling of various combinations:
After
After without causal relationship
Post-infectious disorders are not subtypes of infectious disorders (unless the disorder is itself an infectious disease). The |After (attribute)| is used for linking post-infectious disorders with their associated infections.
After with causal relationship
Before
During
During without causal relationship
During with causal relationship
Sequelae
Naming conventions for sequelae
Naming conventions for surgical sequelae (temporal relationship but no causal relationship)
Naming conventions for surgical sequelae complications (temporal relationship and causal relationship)
Stated view of 123948009 |Disorder following viral disease (disorder)
Stated view of 713890008 |Hypoxemia during surgery (disorder)
Stated view of 698737005 |Obstructive hydrocephalus due to and following meningitis (disorder)|
(finding)
Definition status
Primitive
Because 'Allergy to X vaccine' represents the propensity to an allergic reaction to any component (including excipients) of a vaccine rather than the modeled active ingredient(s), these concepts cannot be sufficiently defined. As a result, there will not be subsumption between "Allergy to X vaccine" concepts.
Exceptions: Grouper concept 863903001 |Allergy to component of vaccine product (finding)| is modeled as sufficiently defined and subsumes the remaining concepts.
Attribute: Has realization
Attribute value = 472964009 |Allergic process (qualifier value)|
Allergy to X vaccine concepts should have one and only one |Causative agent| attribute.
Concepts representing "vaccine product containing only" should not be used in modeling Allergy to X vaccine concepts.
FSN
Use the following pattern for the FSN; align terming and case sensitivity with the FSN for the concept that represents the vaccine product that is the cause of the allergy.
Allergy to component of <Causative agent FSN> (finding)
For example,
Allergy to component of vaccine product containing Hepatitis A virus antigen (finding)
Allergy to component of vaccine product containing Streptococcus pneumoniae antigen (finding)
Allergy to component of vaccine product containing Clostridium tetani and Corynebacterium diphtheriae antigens (finding)
Allergy to component of vaccine product containing Measles morbillivirus and Mumps orthorubulavirus and Rubella virus antigens (finding)
Preferred Term
Use the following pattern for the PT; align terming and case significance with the PT for the disorder that is the target of the vaccine. For multiple ingredient vaccine products, the disorders must be listed in alphabetical order and separated by the word "and".
Allergy to <disorder> vaccine
Allergy to <disorder> and <disorder> vaccine
Allergy to <disorder> and <disorder> and <disorder> vaccine
For example,
Allergy to Hepatitis A vaccine
Allergy to pneumococcal vaccine
Allergy to diphtheria and tetanus vaccine
Allergy to measles and mumps and rubella vaccine
For national extensions modeling using "vaccine containing only" product concepts, these disorder-based descriptions will need to reflect "only" to eliminate duplicate descriptions.
Synonyms
A synonym corresponding to the FSN is required.
Synonyms beginning with the disorder that is the target of the vaccine are allowed. For multiple ingredient vaccine products, the disorders must be listed in alphabetical order and separated by the word "and". Note that these are not true synonyms; they may be updated and identified as "near-synonym" descriptions when that functionality becomes available although that would also potentially require updating the PT.
For example,
Hepatitis A vaccine allergy
Pneumococcal vaccine allergy
Diphtheria and tetanus vaccine allergy
Measles and mumps and rubella vaccine allergy
For national extensions modeling using "vaccine containing only" product concepts, these disorder-based descriptions will need to reflect "only" to eliminate duplicate descriptions.
When modeling, it is challenging to differentiate when trunk vs. trunk plus branches is intended.
NA
An arterial trunk: a single tube
The most common in clinical use.
The meaning of the word artery in injuries and operations is clearly a single tube, the trunk of the named artery, or trunk of the named arterial branch.
A puncture wound of the femoral artery affects the femoral arterial trunk.
A grafting into the popliteal artery is done into the popliteal arterial trunk.
Occlusions of arteries are located by naming the trunk where the occlusion occurs. Occlusions may affect circulation beyond the trunk, however, collateral circulation often mitigates the effects. Thus, it is incorrect to interpret artery to mean the entire subtree in any of these usages.
An arterial tree organ
There are only two complete arterial tree organs (the systemic arterial tree arising at the aortic valve, and the pulmonary arterial tree arising at the pulmonary valve) that are readily named as such. They are seldom referred to by disorders or procedures.
A venous trunk
As with the clinical usage of the word artery , clinical usage of the word vein generally refers to the trunk and not the entire tree
A venous tree organ
There are only eleven venous tree organs that are readily named as such.
128260003 |Pulmonary artery within lung (body structure)|
45341000 |Structure of trunk of pulmonary artery (body structure)|
Venous
430757002 |Structure of pulmonary vein great vessel (body structure)|
Nonexistent
There is no concept for Pulmonary vein within lung.
Central, peripheral, cerebrovascular systems
Common carotid artery, artery of neck
Intracranial, extracranial vascular system
Tree-structured organs
See Tree-structured organs elsewhere, re: regional sections of venous and arterial tree organs.
The word artery
Meanings of artery
Artery
This clinical usage of artery varies from the definition of the FMA, which defines artery as a subdivision of an arterial tree (organ) which consists of branching sets of tubes (arterial trunks) that form a tree; together with other arterial trees (organ parts), it constitutes an arterial tree (organ). The FMA definition corresponds to the third meaning of artery above.
The word vein
Vein
Vein
This clinical usage of vein varies from the definition of the FMA, which defines vein as a subdivision of a venous tree (organ) which consists of branching sets of tubes (venous trunks) that form a tree; together with other venous trees (organ parts), it constitutes a venous tree (organ). The FMA definition corresponds to the third meaning of vein above.
Trunk of vein, vein as a tree structure
Inactivation
All concepts with the name pattern vein x and its tributaries were inactivated due to ambiguity about their meanings. They have MAYBE A links to Structure of vein x and Entire vein x.
The code named Liver structure in CTV3 is equivalent to Liver structure in the diagram above. Both the CTV3 code for Liver structure and the SNOMED RT code for Liver are interpreted to mean Some or all of the liver. Site attributes (PROCEDURE SITE, FINDING SITE) will usually take the value liver structure rather than entire liver , since typically the site of a liver disorder or procedure on the liver is not necessarily the entire liver.
Adding the Entity Structure codes is a convenience to assist with the logic-based aggregation of references to the entity or its parts. The implication of this view is that the E of the SEP triple is the code that should be regarded as the one that represents the real anatomical entity that is named.
For example, the code for entire liver is the one that should correspond to the code for liver in the Foundational Model of Anatomy (FMA). The subtype hierarchy __ for entire liver fits much better with the FMA hierarchies, and indeed it might be possible to completely reconcile SNOMED’s non-Structure components with FMA anatomy.
A database has been developed that categorizes codes in the physical anatomical entity hierarchy according to their status as S structure, P Part or E Entire, and provides the corresponding S and P code for each E code. This should provide some value to implementers. It can help with navigation, coordination with formal ontologies of anatomy, and selection of codes for postcoordination.
Where there were two concepts with the same name, the SNOMED RT code was to become the S code, and the CTV3 code was to become the E code. There are still instances of unrecognized pairing of the RT-CTV3 S-E pair, where neither codes FSN has been changed according to the naming conventions in this document. When these unmatched pairs are identified, it is our practice to change the FSNs accordingly, and to make the E code have a subtype IS-A link to the S code.
Some S codes do not currently have a corresponding E code subtype, and there was no policy that required that such E codes be created during the merger of SNOMED RT and CTV3. However, it is likely that such a policy will be enforced in the future.
The SEP triple may give the impression that all S codes have exactly two children, one E and one P , with all of the remaining descendants placed under P. Again, in the past this degree of modeling consistency was not always followed. Some codes were purposely made subtypes of the S that are not strictly part of the corresponding E.
For example, perirenal tissue is a kidney structure but not a part of the kidney. It is used to define perirenal abscess so that it is subsumed by renal abscess. While a perirenal abscess is not strictly within the substance of the kidney, it is still considered a kind of renal abscess, and the S anatomy hierarchy is used to support this inference.
This policy has introduced undesirable variation and arbitrariness into the terminology, and future revisions will seek to eliminate these variations. Where a code is needed for a site that is really meant to extend to entities that are not part of any kidney, this will be made clear in the name, e.g. Structure of kidney and perirenal tissue.
The E code needs to be interpreted with care when the x name refers to entities that do not have the property of identity, meaning that they are not countable wholes, or could be interpreted as non-countable. In this circumstance, the interpretation of E means some portion of the thing being named.
For example, tissue and types of tissue such as fascia, muscle, tendon, bone tissue, connective tissue, skin, mucosa/mucous membrane, nerve tissue, etc. Muscle, tendon, bone and skin can identify a type of tissue as well as an individual organ of that type. Bone tissue has no identity, but a particular bone does have identity.
To use skin as the archetypal example, the E code for skin of finger means a portion of the skin of a finger, so all of its subtypes must also be portions of skin. The S code for skin of finger then has a subtype P which would mean proper part of a portion of skin of finger. This admits subtypes that are not kinds of skin, but may be parts of skin, including layers, e.g. epidermis of finger (meaning a portion of epidermis of finger) could be a proper part of a portion of skin of finger.
We regard the E code for x tissue, x layer to have the meaning portion of X tissue , and therefore regional subdivisions of tissue types are direct subtypes.
For example, transitional epithelium of urinary tract, as an E kind of code, should be a supertype of transitional epithelium of urinary bladder. The reason is that (portion of) transitional epithelium of urinary bladder is a kind of (portion of) transitional epithelium of urinary tract.
We also deal with layers the same way.
For example, we regard serosal layer and serosa tissue as meaning the same thing, since all serosal tissue is conifigured as a layer, and it can’t be a serosa without being a layer; and their E codes mean portion of serosal layer or portion of serosal tissue.
As another example, layer of retina would be a supertype of nerve fiber layer of retina, and also a supertype of retinal epithelium, where retinal epithelium represents a portion of the epithelium of the retina and is therefore a kind of (portion of) a layer.
The identity/countability issue extends to a problem differentiating groups of entities from one of the group.
For example, consider x = lymph node group , y = lymph node. In this case, the group should be linked to the member via an appropriate Relationship(not yet in SNOMED CT), such as has-member. In those cases where y is always necessarily a member of group x, it could be linked via a member-of Relationship(also not yet in SNOMED CT).
What does part of mean?
There are several possible ways of interpreting part of. In SNOMED CT, A part of B means that in normal anatomy, the entire structure A is structurally included in B. Another way of saying it is that A is part of B if there is no part of A that is not also part of B.
For example, the humerus is not part of the shoulder region, because the distal humerus is part of the humerus, and the distal humerus is not part of the shoulder region.
We do not use part of for non-anatomical meanings, such as grouping tests together in batteries, nor do we use it to indicate Relationships that are not strict anatomical inclusion.
Some recent work has begun to differentiate between part of that is reflexive (that is, an entity is in some sense a part of itself , much the same that a set can be viewed as a subset of itself), versus proper part of , where an entity cannot be a proper part of itself. For now, we regard part of Relationships as implying strict partonomy.
There is sometimes confusion about parthood as opposed to location.
For example, an embryo is not part of a mother's body, but a kidney is. The anatomy section is composed mainly of canonical parts; but a few abnormal parts are included to permit them to be used as the location of tumors or injuries.
For example, a Meckels diverticulum is a body structure that is part of the small intestine, and it is also a morphological abnormality. Likewise some stomas and other post-surgical structures are considered part of the body. A transplanted liver or kidney would be considered part of the body, as a post-surgical structure, even though the transplanted organ is not genetically identical. Likewise transplanted bone marrow is part of the body.
Non-living implants and devices, and foreign bodies, on the other hand, are considered to be located in the body, but not part of the body.
The currently distributed part of Relationships need to be much more extensively modeled and quality assured. At present they are not defining , that is, their Characteristic Type in the relationship file is additional, and, therefore, they do not affect the classifier behavior. A substantial amount of effort has gone into a draft of the updated part of Relationships; these will require review and approval before incorporation into the release. This will eventually result in the SEP triplet structures and part of relations being strictly paralleled. It is a matter of time to implement and quality assure the changes.
The SEP structure, combined with the inference mechanism that is used with SNOMED CT, allows us to take advantage of anatomical Relationships to infer subsumption, IS_A Relationships between disorders, procedures, and other entities without reference to part of Relationships. The SEP structure also permits us to sufficiently define anatomical structures without reference to part of Relationships (making them necessarily true , but not among the necessary and sufficient conditions).
For example, the Structure of left hand can be sufficiently defined as a hand structure with laterality = left. This definition is sufficient. Converting the part of Relationships to have Characteristic Status = defining will require significant changes to the current model.
Points, lines, and surfaces can be considered to be massless. The FMA calls these immaterial. It is important to differentiate the codes/names for these entities from those that are intended to represent entities that have mass. At present, the concepts under anatomical spatial entity represent massless entities. Massless entities are not represented using the SEP model. It is conceivable that users may want to reference parts of a surface, and to enable this we would need to apply the SEP model to anatomical spatial entities, or else adopt defining part of Relationships.
This attribute provides information on whether a body structure is left, right, or bilateral. It is applied only to bilaterally symmetrical body structures which exist on opposite sides of the body.
With the addition of lateralized content in the International Release, the need for unspecified unilateral concepts is removed, as well as potentially dangerous, if used directly in a patient record. Unilateral concepts will not be accepted.
Conventions for merging concepts from SNOMED RT and Clinical Terms v.3
S concepts without a corresponding E concept
S Structure codes can subsume entities other than E or P
Countable vs non-countable E entities
Tissues, layers, membranes: portions
Groups
Can the SNOMED CT relationships table be used to construct a part of hierarchy?
Why are part of relationships not defining?
Entities with mass versus purely spatial massless entities
Attributes used to define body structure concepts
Laterality
Unilateral
Bone structure of proximal right humerus (body structure) - proximal is regional part of humerus
Bone structure of shaft of left femur (body structure) - shaft is regional part of femur
Bone structure of phalanx of left finger (body structure)
🔴 incorrect
Structure of nail of toe of right foot (body structure)
🔴 incorrect , neither 'right nail' nor 'right toe' is correct
Note, hand/foot is redundant when an individually named finger, e.g. index finger, or the great toe has been specified in a description. For example,
Bone structure of phalanx of left index finger (body structure)
🟢correct
Bone structure of phalanx of index finger of left hand (body structure)
🟠 it is not wrong, but 'hand' is redundant
Bone structure of phalanx of left index finger of hand (body structure)
🟠 it is not wrong, but 'hand' is redundant
Lateral half of Y
Y represents any anatomy structure that is symmetrical on the body's middle-line which cannot be lateralized. However, the lateral half of Y can have laterality, e.g. right half of head.
{Part} of X or Y
{Part} represents any constitutional or regional part of anatomical structure of X or lateral half of Y.
Structure of finger of left hand (body structure)
🟢 correct
Structure of left finger (body structure)
🔴 incorrect
Bone structure of phalanx of finger of left hand (body structure)
Structure of + {part} + left/right + X or Structure of + {part} + left/right + half of Y
Special cases that are different from the above two common term patterns
Finger/toe
Structure of + {non lateralizable part} + left/right lung
Causative agent (attribute): Substance (substance) or one of its descendants, if known
Pathological process (qualifier value) hierarchy
In order to fully describe the full range of hypersensitivity responses, there are qualifier values in the Pathological process (qualifier value) hierarchy. (See also Qualifier Value page).
Allergic reaction
Allergic and nonallergic hypersensitivity (pseudoallergic) disease
Allergic and nonallergic hypersensitivity (pseudoallergic) disposition
Figure: Stated view of 15920201000119103 |Allergic reaction caused by fish (disorder)|
Figure: Stated view of 838367000 |Allergic rhinosinusitis caused by Aspergillus (disorder)|
Figure: Allergic and nonallergic hypersensitivity (pseudoallergic) disposition example, stated view of Allergy to nut (finding)
Figure: Allergic disposition (finding) model in stated view
Figure: Nonallergic hypersensitivity (pseudoallergic) reaction model in stated view
Figure: Stated view of Intolerance to substance (finding) model
Figure: Stated view of Intolerance to drug (finding)
Definition status
Primitive
Note: Because 'Adverse reaction to X vaccine' represents the propensity to an adverse reaction to any component (including excipients) of a vaccine rather than the modeled active ingredient(s), these concepts cannot be sufficiently defined. As a result, there will not be subsumption between "Adverse reaction to X vaccine" concepts.
Exceptions: Grouper concepts 293104008 |Adverse reaction to component of vaccine product (disorder)|, 219075006 |Adverse reaction to component of vaccine product containing bacteria antigen (disorder)|, and 408672009 |Adverse reaction to component of vaccine product containing virus antigen (disorder)| are modeled as sufficiently defined and subsume the remaining concepts.
Adverse reaction to X vaccine concepts should have one and only one |Causative agent| attribute.
Concepts representing "vaccine product containing only" should not be used in modeling Adverse reaction to X vaccine concepts.
FSN
Use the following pattern for the FSN; align terming and case sensitivity with the FSN for the concept that represents the vaccine product that is the cause of the adverse reaction.
Adverse reaction to component of <Causative agent FSN> (disorder)
For example,
Adverse reaction to component of vaccine product containing Hepatitis A virus antigen (disorder)
Adverse reaction to component of vaccine product containing Streptococcus pneumoniae antigen (disorder)
Preferred Term
Use the following pattern for the PT; align terming and case significance with the PT for the disorder that is the target of the vaccine. For multiple ingredient vaccine products, the disorders must be listed in alphabetical order and separated by the word "and".
Adverse reaction to <disorder> vaccine
Adverse reaction to <disorder> and <disorder> vaccine
Adverse reaction to <disorder> and <disorder> and <disorder> vaccine
For example,
Synonyms
A synonym corresponding to the FSN is required.
Synonyms beginning with the disorder that is the target of the vaccine are allowed. For multiple ingredient vaccine products, the disorders must be listed in alphabetical order and separated by the word "and". Note that these are not true synonyms; they may be updated and identified as "near-synonym" descriptions when that functionality becomes available although that would also potentially require updating the PT.
For example,
Hepatitis A vaccine adverse reaction
Pneumococcal vaccine adverse reaction
The following illustrates the stated and inferred view for top level grouper 293104008 |Adverse reaction to vaccine product (disorder)|:
The following illustrates the stated view for top level grouper 219075006 |Adverse reaction to vaccine product containing bacteria antigen (disorder)|:
The following illustrates the inferred view for top level grouper 219075006 |Adverse reaction to vaccine product containing bacteria antigen (disorder)|:
The following illustrates the stated view for single ingredient vaccine 293126009 |Adverse reaction to vaccine product containing Hepatitis A virus antigen (disorder)|:
The following illustrates the inferred view for single ingredient vaccine 293126009 |Adverse reaction to vaccine product containing Hepatitis A virus antigen (disorder)|:
The following illustrates the stated view for multiple ingredient vaccine 293125008 |Adverse reaction to vaccine product containing Measles morbillivirus and Mumps orthorubulavirus and Rubella virus antigens (disorder)|:
The following illustrates the inferred view for multiple ingredient vaccine 293125008 |Adverse reaction to vaccine product containing Measles morbillivirus and Mumps orthorubulavirus and Rubella virus antigens (disorder)|:
The life phase of pregnancy-related findings and disorders is applied using the Occurrence (attribute). A concept must identify:
Which actor (mother or the fetus/neonate) does the circumstance relate
In which life phase of the actor does the condition necessarily relate
In the majority of circumstances, the actor to which the condition relates is straight forward: mother or fetus or neonate.
For example,
Antenatal care relates to both the mother and fetus/neonate
Antenatal depression clearly relates to the mother
Short cord with antenatal problem directly relates to the fetus
Other instances such as Intrapartum hemorrhage due to marginal placenta previa may not be so clear without explicit modeling, as hemorrhage with placenta previa can relate to the fetus or mother.
The word perinatal within finding terms is problematic, because it almost always relates to the fetus/neonate. Due vigilance is required to exclude the rare possibility that the condition could relate to the mother. Perinatal can refer to the mother alone (perinatal depression) or to a time period relating to the fetus until the neonate is seven days old.
This situation creates two problems:
#1
The term perinatal is a term with widely varying definitions across countries due in part to legal variations in the time period that defines stillbirth.
The term neonatal generally describes an infant within the first 28 days. Where the condition relates to an infant within the first seven days, the term early neonatal is allocated. The term late neonatal is used from day eight to 28 (WHO, 1992). Although these descriptions are used widely, they are not universally accepted worldwide. These time periods are useful, however, in modeling existing content which was derived from WHO sources.
Future content should use the term neonatal unless a valid use case can be supported in the content request to distinguish between the early and late neonatal period.
#2
The terming of the perinatal period for the fetus and neonate is problematic as there is not a clinically useful name for the actor that covers this entire temporal period. It is possible that baby might be applicable, i.e., Perinatal disorder of baby , but this is not used clinically. To create an explicit FSN, the rather ungainly term |[Clinical finding] of fetus and/or early neonate| has been used. This problem is anticipated to be temporary, as new content will be steered to explicitly state whether the condition relates to the fetus or to the neonate.
In relation to the neonate, there is a clinical and epidemiological distinction between the early neonatal period and the late neonatal period. Conditions in the immediate (early) neonatal period are largely influenced by intrauterine conditions; those in the late neonatal period are more influenced by early extrauterine life. This distinction is important as perinatal disorders historically were often considered a concatenation of disorders occurring in the fetal phase and the early neonatal phase. However, one unresolvable difficulty with this definition is that there is no international agreement in the definition of perinatal phase , which has variable definitions:
WHO = 22 completed weeks of gestation and ends seven completed days after birth
UK = the time from fetal viability from about 24 weeks of pregnancy up to seven days of life
USA = 28 weeks of gestation to the end of the seventh day of life
Australia = 20 completed weeks of gestation and ends 28 completed days after birth
Maternal time period values can be found in the subhierarchies below:
Generally, it is clear what the appropriate value is, but some knowledge is required to distinguish the correct choice in some circumstances. Definitions have been added to aid in correct selection.
For example,
In relation to postpartum uterine hemorrhage , this would be modeled using an Occurrence (attribute) of Postpartum period. The puerperium is generally defined as the period within 42 days after birth, and thus, the postpartum period relates to this six-week timeframe. Some conditions can occur more than 6 weeks post-delivery, e.g., postpartum thyroiditis , postnatal depression (onset can range from a few days to a few weeks following delivery, generally in the first 2–3 months following childbirth). In this situation, the choice of the more general Maternal postnatal period should be made.
Similar to the Maternal time periods above, the fetal period is the superordinate as illustrated below. There is no label for the concatenated time of the actor during the fetal and neonatal period within medicine (though colloquially called baby), and so the superordinate is named fetal and/or neonate. Similarly, to find concepts which describe conditions of this global phase requires a preferred term expressing this, but in the case of perinatal conditions relating to the fetus and/or early neonate, the word perinatal is commonly used as a substitute.
Review is ongoing of all disorder concepts containing the phrase fetal or neonatal. The concept 450426006 |Fetal or neonatal period (qualifier value)| will be inactivated, leaving only 1156676003 |Fetal and/or neonatal period (qualifier value)|.
The fetalorneonatal value is historically derived from ICD and may contain legacy context causing ambiguity.
The fetaland/orneonatal period is explicitly designed to subsume the fetal period, the neonatal period , and in rare cases where these two may overlap, as in 1193538001 |Fetal intrapartum second stage and/or early neonatal period (qualifier value).
Model as IS A 362972006 | Disorder of labor / delivery (disorder)| due to X (disorder).
The definition status of the concept 87476004 |Neonatal seizure (finding)| is to remain primitive for two reasons:
The time period where a neonatal seizure may occur (from birth to 44 weeks postmenstrual age) differs from the period usually representing the neonatal phase of life (the first 28 days following birth).
Defining this concept results in incorrect subsumption with types of epilepsy being classified as subtypes. Epilepsy is not a type of seizure, rather an epileptic seizure is a manifestation of epilepsy.
Use of the term obstetric is confusing in regards to both timing and determination of the intended person. Concepts should rather explicitly identify these elements.
Fetal Neonatal Period Values
When modeling a fetal finding or fetal disorder, the |Finding site (attribute)| should not be a fetal body structure unless the structure is unique to the fetal period, such as |Umbilical cord structure (body structure)|.
Note: This is guideline has not been applied to fetal procedures at this point in time.
Fetal and/or neonatal period versus Fetal or neonatal period
Umbilical cord complication
Neonatal seizure (finding)
Use of organism concepts in combination with such LOINC codes implies that a specific organism is seen, detected, identified, isolated, or present.
Use organism X or organism Y when a laboratory report indicates a single isolate is assumed, but the lab is unable (for any reason) to differentiate the result instance.
For example,
703015006 | Human coxsackievirus or human echovirus (finding)|
Use organism X, not organism Y when a laboratory report indicates a class of organisms described by the exclusion of specific Linnaean or non-Linnaean classes. These concepts are found in the organism hierarchy (based on reasonable use cases to avoid a combinatorial explosion). They are a primitive super class, in between the species or species subtype.
For example,
115407004 | Haemophilus influenzae, not b (organism)|
Exception
The common term yeast can refer to two separate classes: 1) a morphologic form of a dimorphic fungus; or 2) an organism in kingdom Fungi that is truly a yeast. Therefore, while the super class yeast is represented as an organism, “X, not organism Y” type concept is represented in the clinical finding hierarchy (as descendant of 769070007 |Yeast detected (finding)|) since one potential meaning of use is a diagnostic morphologic form of an organism rather than an organism itself.
For example,
769071006 | Yeast not Candida albicans detected (finding)|
Use Genus X, not species Y and not species Z when a laboratory report indicates a species of Genus X and confirms that it is not species Y, nor species Z. E.g. Bacillus species, not Bacillus anthracis and not Bacillus cereus (organism).
Use this naming convention only with Genus, species, and subspecies levels of the hierarchy.
Laboratory reports and journal articles may include an organism that could not be serotyped, e.g. E. coli, untypable. The requests for such concepts are declined due to ambiguity. Instead, use the closest taxonomic level in the hierarchy.
Laboratory findings may be reported with a status of preliminary, presumptive, provisional, etc. These typically cover reportable or notifiable lab values. The status of a report is different from the result; it is part of the electronic health application model/message. The requests for such concepts are declined as they are ambiguous and subject to limitless combinations.
Some laboratories report findings indicating a mixed population of bacteria from several classes, e.g. mixed anaerobic Gram negative bacilli. The request for such a concept is added as a clinical finding. The actual organism is unknown, however there is a result, although more general.
Laboratories perform and report on specific tests to identify the absence, as well as the presence, of a particular pathogenic organism. Laboratories typically report negative result values, such as X not seen , X not detected , X not isolated , and no X seen (or identified or isolated) and positive results as X seen , X detected , and X isolated. The following tables includes the acceptable modeling for negative and positive results.
Microbiology Tests: Reporting of Negative and Positive Values with Examples
Lab test type (Observation)
Result value
Example lab test (e.g. SNOMED CT and/or LOINC term)
Example result value
General culture (where implied scale = nominal)
No X isolated (finding)
X (organism)
61594008 |Microbial culture (procedure)|
11475-1 |Microorganism identified in Unspecified specimen by Culture
On its own, an organism concept can only indicate the definition of that organism. Its detection or presence can only be implied when it is paired with other information that may come from the electronic health application and/or from the LOINC observation.
Organism X or organism Y
Organism X, not organism Y
Genus X, not species Y and not species Z
Untypable organisms
Presumptive values
Concepts with presumptive values
Existing concepts with presumptive values are undergoing review for inactivation.
Mixed Organism
Reporting Negative and Positive Results
Associated morphology = X (morphologic abnormality)
Pathological process = Pathological development process (qualifier value)
All of these defining relationships should be grouped to indicate that the abnormal morphology occurs at the finding site, results from a pathological development process, and is present at birth. Where a morphologic abnormality occurs at more than one finding site, or one body structure has multiple morphologic abnormalities, multiple relationship groups should be created and the pathological process and occurrence relationships included in each relationship group.
The following guidelines apply:
A disorder with the word congenital in the FSN should classify under 66091009 |Congenital disease (disorder)|.
Congenital X (morphologic abnormality) concepts are being inactivated hence Congenital anomaly disorder grouper concepts, such as 9904008 |Congenital anomaly of cardiovascular system (disorder)|, should be modeled with an Associated morphology (attribute) of 49755003 |Morphologically abnormal structure (morphologic abnormality)I and a Pathological process relationship.
Whether creating new or revising existing concepts, only use Congenital X (morphologic abnormality) concepts if no non-congenital supertype of that morphologic abnormality is active.
For example, use 399898009 |Misalignment (morphologic abnormality)| not 102283003 |Congenital misalignment (morphologic abnormality)|
When modeling a congenital neoplasm disorder, the attribute-value relationship of Pathological process (attribute) = Pathological development process (qualifier value) is not used.
While some disorders are only congenital or only acquired, some disorders may be either congenital or acquired. The _ acquired_ form should only exist when there is a need to differentiate from the congenital form. Do not model a disorder as acquired if a congenital variant does not exist.
Congenital disorders are modeled using 246454002 |Occurrence (attribute)| of 255399007 |Congenital (qualifier value)|. If the FSN does not include congenital , it should not be modeled as congenital. The precise meaning of the FSN should be followed (e.g. many hereditary disorders have congenital appearances).
For example,
33534005 |Congenital bowing of femur (disorder)| is modeled with 246454002 |Occurrence (attribute)| of 255399007 |Congenital (qualifier value)|
Stated view of 33534005 |Congenital bowing of femur (disorder)|
Acquired disorders are those that originate and manifest after birth. The disorders are associated with a period of life, as opposed to a specific process or structure. All diseases (disorders) that occur after birth are considered acquired.
Generally, concepts that explicitly state acquired in the FSN or in a synonym should be modeled with Occurrence = 767023003 |Period of life beginning after birth and ending before death (qualifier value)|.
For example,
240253004 |Acquired abduction deformity of foot (disorder)| has acquired in the FSN and is modeled with Occurrence = 767023003 |Period of life beginning after birth and ending before death (qualifier value)|.
Stated view of 240253004 |Acquired abduction deformity of foot (disorder)|
Congenital absence can represent at least three different classes of absence:
Total developmental absence of the affected organ/structure
Partial absence of the affected organ/structure
In utero amputation of all or part of the affected organ/structure
Conventional use of the terms aplasia and agenesis often regard these as synonymous. However, proper definitions of these terms suggests a distinction that should be made in the terminology when included in the FSN.
Aplasia - defective development resulting in the absence of all or part of an organ or tissue.
Agenesis - absence of an organ due to nonappearance of its primordium in the embryo. (implies complete absence)
In order to conform to the intended meaning of the FSNs as described by the original source, the following modeling patterns are proposed for congenital absence terms:
According to the American Medical Association, the periods of life in the postnatal period include all periods after birth including the neonatal or immediate postpartum period. It may be challenging to differentiate a congenital disorder from a neonatal disorder. A condition may be present at birth, i.e. congenital; however, clinical manifestations may take longer to appear, i.e. during the neonatal period (e.g. 14333004 |Alloimmune neonatal neutropenia (disorder)|).
Congenital versus acquired
Remodeling Acquired Disorders
When revising acquired disorders, remove any acquired morphologies and replace with general parent morphologies, e.g. replace 127560004 |Acquired deformity (morphologic abnormality)| with 6081001 |Deformity (morphologic abnormality)|. Then add Occurrence attribute with a value of 767023003 | Period of life beginning after birth and ending before death (qualifier value)|. One of its children may also be used if the FSN states the period of life, such as Childhood or Adulthood.
Congenital absence
See also relative sections:
Observable Entity Defining Attributes
All attributes with a range constraint for << |Pharmaceutical / biologic product (product)|
Where the MRCM allows Pharmaceutical / biologic product (product) and its descendants as valid values for Observable entity (observable entity), the Pharmaceutical / biologic product (product) subhierarchy is not currently used for values with these attributes in the International Release except for 787859002 |Vaccine product (medicinal product)| and its descendants, which can be used as valid values for this attribute.
Characterizes
This attribute specifies the process which the property describes, and on which the property (of this observable) depends. The process can be very general (e.g. excretion).
For example,
Mass concentration ratio of silver to creatinine in 24-hour urine (observable entity) has 704321009 | Characterizes (attribute)| of excretion process
789098002 |Estimated quantity of intake of potassium in 24 hours (observable entity)| has a 704321009 |Characterizes (attribute)| of administration of substance
This attribute is used to specify the numerator of a relational property types, e.g. ratio, concentration.
For example,
Arbitrary concentration of Varicella-Zoster virus (observable entity) has the 246093002 | Component (attribute) | of Human herpesvirus 3
This attribute is used to specify the entity on which the observation is directly made. It may also be used when the observation is indirect, i.e. when a direct observation cannot be done.
For example,
415974002 | Core body temperature measured at tympanic membrane (observable entity) | has the 704327008 | Direct site (attribute)| of 42859004 | Tympanic membrane structure (body structure) |
This attribute is used to specify the process or activity that is the consequence of realization of the function.
For example,
282097004 | Ability to walk (observable entity)| 719722006 | Has realization (attribute) | of 870595007 |Walking (qualifier value)|
This attribute is used to specify a body site or other location of the independent continuant in which the property exists.
For example,
5310001000004108 |Histologic type of neoplasm of skin (observable entity) | has 718497002 | Inherent location (attribute) | of 39937001 |Skin structure (body structure) |
This attribute specifies the independent continuant in which the quality exists and on which the dependent quality (of this observable) depends.
For example,
307047009 |Core body temperature measured in rectum (observable entity)| has 704319004 | Inheres in (attribute) | of 278826002 | Body internal region (body structure) |
This attribute is used to specify body state, timing, challenges, or other situations that must be true of the entity to be observed.
For example,
Plasma creatinine concentration 7 days post challenge (observable entity) has a Precondition of 7 days post challenge
163033001 | Lying blood pressure (observable entity) | has a 704326004 | Precondition (attribute) | of 102538003 | Recumbent body position (finding) |
This attribute is used to model devices associated with a procedure. This attribute is used to define high-level, general concepts that aggregate procedures according to the device involved.
This attribute is used to describe that a process specifically acts on some entity, e.g. by transporting that entity in or out of the body, i.e. Rate of intake of protein.
For example,
789350001 |Estimated quantity of intake of iron in 24 hours (observable entity)| has a 1003735000 | Process acts on (attribute) | of iron
This attribute is used to specify the continuant (e.g. body structure or organism) that is causally active in the process on which the property depends. It is used to refine the meaning of the process named as the value of 704321009 | Characterizes (attribute)| , or it may simply repeat the meaning that is already there.
For example,
Substance rate of secretion of somatotropin by pituitary following clonidine per os (observable entity) has the 704322002 | Process agent (attribute) | of 56329008 | Pituitary structure (body structure) |.
This attribute specifies the duration of the process characterized by the observable property type.
For example,
Mass rate of excretion of cortisone in 24 hour urine (observable entity) has the 704323007 | Process duration (attribute) | of 123027009 | 24 hours (qualifier value) |
This attribute specifies that the process which the property characterizes has led to the inclusion of a previously not included structure.
For example,
The concept |Presence of direct invasion by primary malignant neoplasm of prostate to seminal vesicle (observable entity)| has a 1003703000 |Process extends to (attribute)| of | Seminal vesicle structure (body structure) |
This attribute is used to specify the substance or process produced by the process characterized by the observable property type.
For example,
Substance rate of excretion of pregnanediol in micromoles per day (observable entity) has a 704324001 | Process output (attribute) | of 28268006 | Pregnanediol (substance) |
This attribute is used to specify the type of feature (i.e. quality, disposition, function, or process characteristic) to be observed. Its values are abstract types of quality (length, odor, concentration) or abstract types of process features (rate, speed).
For example,
Blood glucose mass concentration (observable entity) has the 370130000 | Property (attribute) | of 118539007 | Mass concentration (property) (qualifier value) |
The Property (qualifier value) hierarchy contains the following:
118538004 | Mass, a measure of quantity of matter (property) (qualifier value) |
726527001 | Weight (property) (qualifier value) |
Very rarely is the physics definition of weight used. When the term weight is used, it is most often referring to mass , as further demonstrated by the units of measure i.e., grams, kilograms, etc. Unless units specific to the physics definition of weight are specified using Newtons, assume that mass is implied.
To summarize, always use the mass qualifier value unless a concept is requested with Newton units that specifically refer to weight.
This attribute is used to specify the denominator of a relational property type, e.g. a ratio or proportion.
For example,
Urine alpha aminobutyrate to creatinine ratio (observable entity) has 704325000 | Relative to (attribute) | 15373003 | Creatinine (substance) |
Neutrophils per 100 leukocytes in blood (observable entity) has 704325000 | Relative to (attribute) | 702962009 | Population of all leukocytes in portion of fluid (body structure) |
This attribute is used to specify the denominator of a relative relational property, such as a ratio of ratios.
For example,
Relative substance concentration of cerebrospinal fluid IgM to plasma IgM (observable entity) has 719715003 | Relative to part of (attribute) | of 50863008 | Plasma (substance) |
This attribute is used to specify the scale of the result of an observation or a diagnostic test (i.e., quantitative, qualitative, semi-quantitative).
This attribute is used to specify the systematic method of an observation.
For example,
Presence of Brucella abortus antibody in serum by latex agglutination (observable entity) has the 246501002 | Technique (attribute) | of 703448004 | Latex agglutination test technique (qualifier value) |
146611000146107 |Breast Imaging Reporting and Data System assessment category (observable entity)| has the 246501002 | Technique (attribute) | of 1348266008 |Breast Imaging and Reporting and Data System (assessment scale)|
This attribute is used to specify the timing of an observation.
For example,
Substance concentration of acetone in urine (observable entity) has the 370134009 | Time aspect (attribute) | of 123029007 | Single point in time (qualifier value) |
This attribute is used to specify a disposition, what the disposition is towards, i.e. a specific triggering agent, or more generally, participant in the realization of the disposition.
For example,
Quantitative susceptibility of Pseudomonas aeruginosa to amikacin in microbial isolate by disk diffusion (observable entity) has 704320005 | Towards (attribute) | of 387266001 | Amikacin (substance) |
This attribute is used to specify the units used in assigning a value to an observation.
For example,
Basophils per 100 leukocytes (observable entity) has the 246514001 | Units (attribute)| of 415067009 | Percentage unit (qualifier value) |
This attribute is used to specify the instrument or equipment utilized to execute an action. Using device is appropriate when the device is actually used to carry out the action that is the focus of the procedure.
For example,
415921007 | Temperature of forehead using skin strip thermometer (observable entity) | has 424226004 | Using device (attribute) | of 448916003 | Skin strip thermometer (physical object) |
Neoplasm
Tumor vs. neoplasm
The word tumor has two primary meanings: a mass, regardless of whether it is neoplastic or not; or a neoplastic mass. The term neoplasm is preferred since it is less ambiguous than tumor. The word tumor is acceptable as a synonym but not as a preferred term.
For example,
92385005 |Benign neoplasm of small intestine (disorder)|
Primary malignant neoplasm
Previously in SNOMED CT, the hierarchy of 372087000 |Primary malignant neoplasm (disorder)| was defined by using an Associated morphology (attribute) relationship to <<86049000 |Malignant neoplasm, primary (morphologic abnormality)|. 86049000 |Malignant neoplasm, primary (morphologic abnormality)| and 367651003 |Malignant neoplasm of primary, secondary, or uncertain origin (morphologic abnormality)| have been inactivated in the November 2022 release and replaced with 1240414004 |Malignant neoplasm (morphologic abnormality)|.
Primary malignant neoplasm disorders are now defined with a role group combining:
finding site
associated morphology
pathological process with a target value of 1234914003 |Malignant proliferation of primary neoplasm (qualifier value)|
For example,
Figure: Stated view of 93825008 |Primary malignant neoplasm of heart (disorder)|
Figure. Inferred view of 93825008 |Primary malignant neoplasm of heart (disorder)
Precoordination of the metastatic malignant neoplasm with both the primary and metastatic sites is not allowed. Having both metastatic malignant neoplasm from x body structure to y body structure in a single concept results in a combinatorial explosion of all possible malignant neoplastic morphological cell types, with all possible body sites of the primary malignancy, and with all possible sites of the metastases. Users are instead directed to record two separate concepts.
SNOMED CT joins ICD-O, ICD-10, and ICD-11 where metastatic malignant neoplasm of site x is uniformly interpreted to mean metastasis has occurred to site x. To make this explicit in SNOMED CT, the following terming has been adopted:
FSN: Metastatic malignant neoplasm to x body structure (disorder)
PT: Metastatic malignant neoplasm to x body structure
SYN: Secondary malignant neoplasm of x body structure
SYN: Metastatic malignant neoplasm of x body structure
For example,
FSN: Metastatic malignant neoplasm to foot (disorder)
PT: Metastatic malignant neoplasm to foot
SYN: Secondary malignant neoplasm of foot
SYN: Metastatic malignant neoplasm of foot.
Metastatic disorders are defined by a role group containing the finding site and specific metastatic morphologic abnormality.
For example,
Figure: Stated view of 105041000119109 |Metastatic squamous cell carcinoma to lung (disorder)|
Figure: Inferred view of 105041000119109 |Metastatic squamous cell carcinoma to lung (disorder)|
Disorder concepts defined with 1240414004 |Malignant neoplasm (morphologic abnormality)| may have cancer added as an acceptable synonym. The term cancer should not be used in the FSN or preferred term. Neither should it be used in descriptions for concepts that are more specific subtypes of the top level malignant neoplasm grouper (i.e., where the morphology is a specialized cell type).
The term cancer may also be used in the 'metastatic cancer to x body structure ' synonym description where the morphological type of metastatic neoplasm is unknown, i.e., it is defined with 14799000 |Neoplasm, metastatic (morphologic abnormality)|.
When modeling neoplasia, distinguish structure from process. Do not use neoplasia in the FSN to identify the structure (even though it implies it). Use 126537000 |Neoplasm of bone (disorder)|, not neoplasia of bone.
Neoplastic disease refers to the process of neoplasia , leading to the formation of a neoplasm.
A neoplasm is defined as a growth of tissue no longer under normal control. A hamartoma is defined as a benign, self-limiting growth of disorganized mature cells normally found in the region, representing faulty development. SNOMED CT has disorder (and morphologic abnormality) concepts and subtypes representing neoplasia, hamartomas, and tumors.
The SNOMED CT concept 399981008 |Neoplasm and/or hamartoma (disorder)| has six subtypes:
angiomatosis
hamartoma
hemangioma
lymphangioma
The SNOMED CT concept 400177003 |Neoplasm and/or hamartoma (morphologic abnormality)| also has six subtypes:
angiomatosis
blood vessel tumor
hamartoma
lymphatic vessel tumor
The word nevus has many different meanings. The differences are generally based on answers to the following questions:
Is it necessarily on the skin? Or can it be located in mucosal sites or other sites?
Is it necessarily visible? Or can it be in internal locations such as gastric mucosa, etc?
Is it necessarily present at birth? Or can it occur later in life?
Is it necessarily dark and made of melanocytes? Or can it be non-pigmented, or made of other types of cells?
Some common meanings of nevus based on some combinations of answers to the questions are as follows:
A birthmark, that is, any visible spot on the skin or oral mucosa present since birth, regardless of tissue of origin, excluding benign neoplasms.
Any benign cluster of melanocytes, regardless of location, and regardless of pigmentation, whether present since birth or appearing later.
Any cutaneous hamartoma. This excludes non-cutaneous sites, and excludes neoplasms and ectopic tissue, such as choristomas.
As a result of this wide variation in meaning, any SNOMED CT FSN containing the word nevus may be ambiguous. For example, the term vascular nevus may mean:
Congenital blood vessel tumor in the skin
Congenital blood vessel hamartoma or neoplasm that is visible somewhere (not only the skin, but also the mucosa, whether visible externally or not)
Congenital blood or lymphatic vessel tumor in the skin
Congenital blood or lymphatic vessel hamartoma or neoplasm that is visible somewhere
A better FSN for vascular nevus (morphologic abnormality) would be vascular hamartoma (morphologic abnormality). Likewise, a better FSN for congenital vascular nevus (disorder) would be congenital vascular hamartoma (disorder).
In those cases where common clinical usage of a term containing nevus is unambiguous, there is no need to inactivate the description or the concept.
Overlapping neoplasm concepts refer to a neoplasm that overlaps two or more adjacent sites. For clarity, the phrase overlapping sites should be included in the descriptions for the FSN and PT for new overlapping neoplasm content.
For example,
188247000 | Malignant neoplasm of overlapping sites of bladder (disorder)|
For modeling an overlapping neoplasm concept, if the concept refers to contiguous sites involving more than one anatomical site, then a separate role group is used for each finding site.
However, assigning a role group for each finding site does not sufficiently define a concept but merely indicates the presence in both sites of a neoplasm. Where a relevant primitive existing overlapping neoplasm concept is available, this can be used as a stated primitive parent to sufficiently define the concept.
For example,
Sufficiently defined concept 721624000 |Primary adenocarcinoma of overlapping sites of esophagus (disorder)| has a stated primitive parent of 187824009 |Malignant neoplasm of overlapping sites of digestive system (disorder)|.
When modeling a congenital neoplasm disorder, the attribute-value relationship of Pathological process (attribute) = Pathological development process (qualifier value) is not used.
Organism concepts are generally considered in scope for inclusion in the International Edition, with the following exceptions and considerations:
Microorganisms are typically included in the International Edition because they may be human pathogens, opportunistic pathogens in immunocompromised individuals, or organisms of relevance to clinical laboratory reporting, including animal pathogens.
Macroorganisms are included in the International Edition when they are relevant to human medicine or public health, or when requested by more than one SNOMED International Member country. Otherwise, they may be authored in the Veterinary Extension, which is maintained by the Veterinary Terminology Services Laboratory (VTSL) at Virginia Tech. Content from the Veterinary Extension is not promoted to the International Edition unless it subsequently meets the criteria for relevance to human medicine, public health, or demonstrated international demand.
Breeds are restricted to the veterinary domain and are not represented in the International Edition.
For represented organisms, the International Release will include the principal taxonomic ranks needed to support classification. Intermediate ranks (e.g., Subphylum, Order, Suborder, Infraorder) should be added only when they provide a clear structural, modeling, navigation, maintenance, or reporting benefit. In particular, an intermediate taxon should be included when it is a structurally necessary node for one or more existing concepts that would otherwise be incorrectly classified. Once an intermediate rank is introduced, sufficient sibling taxa at that rank should also be represented, where appropriate, to maintain a complete and internally consistent hierarchy.
When modeling organisms with qualifiers, the qualifier should be placed in front of the organism name.
For example, a non-Linnaean class of bacteria described by morphology
Growth morphology is not an always and necessarily true characteristic of an organism and therefore should not be considered an intrinsic characteristic. The terms representing growth morphology such as Branching Gram-positive bacillus present or Gram-positive cocci in chains present are usually used for reporting a visual finding that is a characteristic of a sample. These terms should be represented as findings.
For example, 1231428004 | Beaded branching Gram-positive bacilli present (finding) |
A number of qualifiers might be valid (e.g. aerobic microaerophilic, motile curved gram-negative bacteria). To determine the sequence, the decision-making process is stepwise as follows:
Determined on a case-by-case basis
Highly dependent on fitting in with the model limitations
Based on Bergey’s Manual of Systematic Bacteriology as the primary reference
When requesting a new qualifier, an acceptable reference must be provided. Concepts with valid qualifiers are added to the International Release.
Only authoritative taxonomic groupings are added to the SNOMED CT International Release. When requesting new organism concepts, authoritative references must be provided. Acceptance is determined on a case-by-case basis by authors. These concepts may evolve over time as the names evolve.
The terms “complex” and “group” are often used in scientific papers. Laboratories then reflect the words they see in those papers in their local descriptions. However, the terms used in scientific papers are not authoritative taxonomic groupings; rather, they are just concepts used for ease of publication and grouping sets of organisms that are similar in certain functions or structure.
Implementers must be aware these types of concepts may evolve over time. As the sophistication of microbiology labs increases, the “members” of each complex may change and the complex concepts actually become obsolete. For example, this has occurred for some of the Centers for Disease Control and Prevention (CDC) groups where a number of these concepts have actually been given names and the CDC group name is archaic.
When requesting a new group or complex, an acceptable authoritative reference must be provided. The reference should clearly specify the list of species and subspecies associated with the complex/group.
Existing complex or group concepts, with grouper concepts separate from the genus, but with the same meaning as the genus, will be inactivated in the SNOMED CT International Release.
Descriptions with group or complex as synonyms of the genus, will be deprecated from the SNOMED CT International Release (The genus concept should be used for these concepts).
Microorganism is a common grouping name for organisms, but it does not align with Linnaean classification. Microorganisms are organisms that can only be seen using microscopy. Four major classes could reasonably be assigned to microorganism at the highest levels. Viruses, prions, bacteria and archaea are all microscopic. Fungi are both microscopic and macroscopic and this is also true for animals. Finally, there are examples of organisms (e.g. Phylum Nemata) that are macroscopic as adults but diagnostic life-cycle stages such as eggs and larvae are microscopic. Assigning and maintaining all subtypes to this seemingly familiar organism group is problematic and would be time and resource intensive. This concept has been deprecated and will not be added to the organism hierarchy.
Requests for new concepts are evaluated on a case-by-case basis.
It is important to understand the meaning from the requestor and determine how it can be modeled.
These concepts may evolve over time as the names evolve.
"X-like” organism is a term construction used in the medical lexicon that is outside the classic Linnaean taxonomy. ”X-like” organisms are identified by their similarity to some other organism. There is no single category or use of X-like organism terms; the meaning of these terms is context-dependent and open to interpretation when no context is provided. For many of these terms, the meaning will change with time. In some cases, this leads to a chain of terms that remains in colloquial use but loses value and place in the scientific literature. In addition, while reporting X-like organisms is clinically significant—unlike “untypeable” concepts—they cannot have a specific parent. These concepts are added:
only if clear context is provided by the requester; and
under the highest level concepts in the “organism” hierarchy i.e. direct parents would be Virus, Bacteria, Fungus.
Provisional serotypes, i.e. serotypes that have been defined but not given a number in the antigenic schema, are considered for addition on an ad hoc basis and only if it can be confirmed that this is a reproducible assignment not being duplicated by multiple organizations.
SNOMED International adopted the recommendations of a joint initiative of the European Centre for Disease Prevention and Control (ECDC) and the CDC for the characterization of the different patterns of resistance found in healthcare-associated, antimicrobial resistant bacteria. A panel of international experts convened and drafted a proposal which provides clear consensus definitions. Please refer to the following article for details: Magiorakos, A. Srinivasan, A. Multidrug-resistant, extensively drug-resistant and pandrug-resistant bacteria: an international expert proposal for interim standard definitions for acquired resistance. Clinical Microbiol Infect 2012; 18: 268-281.
Pharmaceutical and Biologic Product
Definition
A top-level hierarchy to clearly distinguish drug products (products) from their chemical constituents (substances)
Purpose of the SNOMED CT Medicinal Product hierarchy
The SNOMED CT Medicinal Product hierarchy provides concepts to describe medicinal products at various levels of abstraction with international applicability and support for interoperability in patient care and health data analysis. It provides a foundation from which member nations can extend with additional concepts suitable for their own healthcare culture and practice, or to which existing terminology can be mapped if required.
This document describes the model for the concepts in the medicinal product hierarchy in the international edition of SNOMED CT; when populated, this model will provide:
concepts in the international edition to meet the core use cases
a foundation for national medicinal product terminologies
For member nations with an existing terminology, the model underpinning the concepts will facilitate both direct use or mapping
For member nations without an existing terminology, the concepts provide a consistent starting set of concepts and a model to develop from
This document also provides a description of how aspects of the SNOMED medicinal product hierarchy correspond with the suite of standards in ISO (Internal Organization for Standardization), collectively known as the "Identification of Medicinal Products standards" (IDMP). These IDMP standards provide a conceptual model for the unique identification of a medicinal product globally and standard terminology concepts to support this (for example, to describe substances and dose forms). The domain of use for the IDMP standards is primarily the regulatory domain, but since regulatory information is the source and underpinning for the description of medication and medicinal product concepts in a clinical/patient care medicinal product terminology, both internationally and nationally, it is important that the SNOMED CT medicinal product model and supporting concepts are in harmony with those standards. Compatibility with the IDMP model for identification of medicinal products will facilitate information flow between the two domains of use (for example, to support pharmacovigilance). However, there is no sense that this harmony entails “full and exact compliance”; there would be little value in exact duplication. The SNOMED CT medicinal product hierarchy therefore provides classes of concepts that are additional to those present in the IDMP model to support the specific SNOMED CT and patient care/health data analysis use cases.
The scope of specification for the concept model for representation of medicinal products in the international edition of SNOMED CT is limited to pharmaceutical and biological products only; products that represent blood products, foods/nutritional supplements, additives, and complementary medicines (including homeopathic products) are currently out of scope. The representation of autologous medicinal products (those created from tissue and administered back to an individual) is also out of scope. Concepts for vaccines also follow the pattern of this model, although only to two of the three "levels" (MP and MPF). Further detail can be found in the .
The international medicinal product model and concepts in the international edition are described in their more abstract form; real or actual products (including branded products and those marketed without a brand name) as authorised by medicines regulatory agencies within jurisdictions are out of scope. Describing the packages in which medicinal products are placed into the supply chain are also out of scope; both of these areas are covered in the national model specification.
This document is written for everyone with an interest in the development, maintenance, and use of medicinal product concepts within SNOMED CT, including those in member nations who are or wish to use medicinal product concepts from the international edition, either directly (in an extension where appropriate) or by mapping, in any national/local medicinal product terminology. It is relevant to those responsible for clinical or research systems using medicinal product concepts in both active medication processes (prescribing, dispensing, and administering medicines) or in recording of medication information, and also particularly to those responsible for systems providing decision support for medication safety.
The main use cases for the medicinal product hierarchy in the international edition of SNOMED CT are as follows:
To provide a consistent and usable set of international medications concepts for member nations to use as a foundation for national medicinal product terminology
For those member nations with an existing terminology, the improved model underpinning the concepts will facilitate both direct use or mapping
For those member nations without an existing terminology, the concepts provide a consistent starting set of concepts and a model to develop from, reducing resource (especially set up costs) and risk in development
SNOMED CT as an ontology is constructed on the principle of an open world view (the existential restriction) with each concept having a distinct fully specified name. The implication of the open world view for the medicinal product hierarchy is that a concept represents the set of (real world) medicinal products that contains "(at least) some substance X as an active ingredient", but may contain other unspecified active ingredient substances. This 'open world' view is useful for analysis and in some types of decision support. However, the regulation of medicinal products for sale/supply is based on the 'closed world' view (the universal restriction), where all active ingredient substances must be explicitly described. This is also the premise for description of medicinal products in the medication process (prescribing, dispensing and administration). Therefore, the Medicinal Product hierarchy differs from other concept hierarchies within SNOMED CT in that some classes of concepts within it are modeled using this 'closed world' view, which states that a concept represents a medicinal product that contains "only substance X as an active ingredient"; no other active ingredient substances are present within it. To implement that "closed world view" with the existing tools and systems of SNOMED CT, the "ingredient count" proxy has been developed. Some description of this is given below, with further detailed information being available in the machine-readable concept model. For further details on the open and closed world views, please refer to the relevant SNOMED documentation and training materials.
IDMP, being a suite of standards developed in and for the regulatory domain, uses a "closed world" view. The active ingredient substance(s) present in a product must be listed in full, with no exceptions, so IDMP exists in the "closed world" view and therefore would be compatible with the "universal restriction" only; the existential restriction is not compatible with the concepts in the IDMP suite of standards, which is particularly important to note for the abstract concepts within IDMP in ISO 11616 (PhPIDs, especially L1, L3 and L4).
In maintaining a medicinal product terminology, concepts are authored to describe those things that exist and can be used in clinical care and/or clinical research. This means that it is the more granular concepts that are usually recognised first, then the less concrete concepts are abstracted from these. In many medicinal product terminologies, this results in there being lowest level child concepts for every parent concept within the model classes. Due to the historic nature of some of the content in the SNOMED CT international edition medicinal product hierarchy, there will be higher level parent concepts (i.e., MP and MPF concepts) that do not have clinical drug concepts associated with them. These MP and MPF concepts may have had clinical drug type concepts associated with them in the past, but the veracity and provenance of the detailed information to support these CD concepts could not be confirmed, so they have been inactivated, whereas the more abstract MP and MPF concepts remain in the international release to support historic data use cases such as analysis and medication profiles.
There is nothing in the specification that deals with availability of medicinal products for use; neither the presence of a concept nor an absence of a concept gives any sense of its availability in the supply chain globally. Indeed, even when a medicinal product ceases to be available anywhere in the global supply chain, its representation will remain as a valid concept in SNOMED CT for use in patient medication history and patient medication profiles. New medicinal products, both from newly authorised therapeutic substances and in new formulations of existing therapeutic substances, are constantly appearing globally. The principles and process for the ongoing maintenance of and addition of new content to the medicinal product hierarchy are being developed as part of the Editorial Guidelines.
The definition of the 763158003 |Medicinal product (product)| concept as providing the scope of the hierarchy is in agreement with the scope of the concept of a medicinal product in IDMP. This is a positive position generally and particularly for any future mapping exercise that might be undertaken, since there should be few concepts that cannot be mapped at some level of granularity. However, in IDMP, and specifically in ISO 11615, the Medicinal Product class represents an authorised medicinal product that consists of one or more Manufactured Items as authorised and available; in this sense it is much more concrete concept than the SNOMED parent concept. This difference is not of great significance other than to understand that the same term ("medicinal product") has a different and more specific meaning in IDMP than in the SNOMED CT medicinal product model. Also, the IDMP ISO 11615 model explicitly describes and includes "combination medicinal products" (also known as 'kit' products, 'component' products, 'multi-component packaged products', etc.) where the package placed into the supply chain contains more than one type of component element (clinical drug) within it; since these are correctly packaged products, and packaged products are out of scope of the medicinal product hierarchy for the international edition of SNOMED CT, these combination products are not represented in this SNOMED CT model.
The |Pharmaceutical / biologic product (product)| hierarchy is comprised of multiple smaller hierarchies. It contains the following semantic tags:
(medicinal product)
(clinical drug)
(medicinal product form)
(product)
Musculoskeletal System
The skeletal system (systema skeletal in Nomina Anatomica) includes bones and cartilage. The bony skeleton includes bones only. The vertebral column is part of the skeletal system and includes the intervertebral discs (fibrocartilage). Individual vertebrae are part of the bony skeleton.
In ordinary usage, bone combines the meanings bone organ and bone tissue.
The 5 anatomical concepts related to bone are:
3138006 |Bone (tissue) structure (body structure)|. Tissue type that makes up bones; a quantity of regular connective tissue consisting of osteocytes and related cells, the intercellular matrix of which is ossified; or any part thereof.
