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,

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 (Uptodate.com) 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.

• https://www.mdpi.com/1467-3045/46/5/251

When creating a lateralized disorder concept, two concepts should be created:

1. concept for the left side

2. concept for the right side

Descriptions

• FSN: <morphologic abnormality> of <right/left> <body structure> (disorder)

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.

The following principles were utilized during the 2026 inactivation and remodeling of concepts within the hierarchies 198609003 |Complication of pregnancy, childbirth and/or puerperium (disorder) and 362972006 |Disorder of labor / delivery (disorder).

Temporal Semantics

The modeling of concepts whose FSNs contain certain words have been standardized by a consistent specified temporal value (with occasional exceptions) as tabulated below:

The notion of complication is explicitly stated in legacy material from ICD to refer to ‘adverse evolution’. The existing descendants of |Complication of pregnancy, childbirth AND/OR puerperium (disorder)| were incomplete and predominantly related to maternal disorders but also historically included a small number of fetal concepts affected by the maternal environment. For these reasons, the following concepts have been inactivated as ambiguous with historical association to their respective separate maternal and fetal grouping superordinates:

• 198609003 |Complication of pregnancy, childbirth and/or puerperium (disorder)|

• 609496007 |Complication occurring during pregnancy (disorder)|

• 199745000 |Complication occurring during labor and delivery (disorder)|

Combined high level maternal and fetal grouping concepts, e.g., Maternal disorder and/or fetal disorder during intrapartum period, have not been added, as these coalesced classes can be located using Expression Constraint Language (ECL).

High level general concepts, e.g., 45828008 |Anemia in mother complicating pregnancy, childbirth AND/OR puerperium (disorder), have been inactivated as ambiguous with historical association to an explicit concept relating to the presence of the condition that does not state that it is complicating, for example, |Maternal anemia during antenatal and/or intrapartum and/or postpartum period|.

In contrast, where the word complicating has been applied to a more limited time phase, e.g., 10742121000119104 |Asthma in mother complicating childbirth (disorder), this concept has been retained, as potentially clinically valuable, but marked as incompletely defined (primitive) due to the notion’s inherent lack of specificity. In this exemplar, 10742121000119104 |Asthma in mother complicating childbirth (disorder), could denote the co-occurrence and impact of asthma on labor but the nuance is not explicit, and the notion could also involve the exacerbation of asthma secondary to the process of labor (or, of course, both interactions could be present). Thus, ‘Asthma in mother complicating childbirth’ is semantically more complex than the simple co-occurrence of ‘asthma with childbirth’ and consequently the concept has to be primitive, as the word complicating here captures the ‘adverse evolution’ of certain conditions away from the norm in the intrapartum state.

Concepts such as 34270000 |Miscarriage complicated by shock (disorder) describe the occurrence of shock in the context of a miscarriage, i.e., the shock would not have occurred without the miscarriage; consequently, such concepts have been inactivated and replaced by new concepts, for example, |Shock due to miscarriage|. It is worth noting that no further temporal information is available in the terming as to whether the shock occurred during and/or after the miscarriage.

Concepts with FSNs such as ‘X affecting pregnancy’ and ‘Y affecting management of pregnancy’ have been inactivated and replaced with explicit concepts of the form: |Disorder of pregnancy due to X|

• For example,

  • 443006 |Cystocele affecting pregnancy (disorder) has been inactivated with historical association to a new concept 1381656002 |Maternal cystocele during antenatal and/or intrapartum period (disorder)

  • 106008001 |Delivery AND/OR maternal condition affecting management (disorder) has been inactivated with historical association to 1269075002 |Maternal disorder during intrapartum period (disorder)

The occurrence value for ectopic pregnancy concepts have been defined as Maternal antenatal period with an associated finding site of |Structure of product of conception|. Where the ectopic is explicitly a fetus, this has also been modeled. For example, 237253003 |Viable fetus in abdominal pregnancy (disorder) is modeled as relating to the abdomen within the maternal antenatal period & the fetus in relation to the fetal period, (as, in this case, a viable fetus is a fetal disorder as well as an abdominal pregnancy). The conceptus is an embryo until the end of the eighth week of pregnancy, and from the beginning of the ninth week until delivery, the conceptus is known as the fetus. The first trimester begins at conception until the end of week 12, so this includes the transition between embryo and fetus at the end of 8 weeks gestation.

An ectopic pregnancy is also defined as NOT being within the uterine cavity, but being located in the abdominopelvic cavity or a substructure. Consequently, 198627000 |Angular pregnancy (disorder)|, which is intrauterine, is NOT considered an ectopic pregnancy. Where the site of the ectopic is stated, e.g., 79586000 |Tubal pregnancy (disorder)|, this is modeled with the finding site |Fallopian tube| and an occurrence of |Maternal antenatal period|.

Concepts relating to miscarriage and abortion are both modeled using a finding site of |Structure of product of conception| and an occurrence of |Maternal antenatal period|, e.g., 59363009 |Inevitable abortion (disorder).

The hierarchy 314908006 |Extra-embryonic structure (body structure)| includes:

• 34863009 |Decidua structure (body structure)

• 78067005 |Placental structure (body structure)

• 74439004 |Chorionic structure (body structure)

• 70847004 |Structure of amnion (body structure)

Disorders of extra-embryonic structures excluding the umbilical cord, e.g., placenta, necessarily relate to the Maternal antenatal/intrapartum/postpartum period, as for example, conditions such as ‘uterine retained products of conception’ extend beyond the end of the third stage of labor and persist into the postpartum period. Other disorders, e.g., 36813001 |Placenta previa (disorder)| relate to only the Maternal antenatal and/or intrapartum time period.

Disorders of the umbilical cord necessarily relate to the fetus and/or neonate. Some concepts also relate to the maternal antenatal and intrapartum temporal period, where the pathogenesis of the connecting structure necessarily impacts on the maternal actor, e.g., 270500004 |Prolapsed cord (disorder). Disorders of cord during the postpartum period are modeled with only |Neonatal period|.

The maternal hypertension hierarchy encompasses all concepts representing hypertension present during the antenatal, intrapartum, or postpartum periods. It includes both conditions arising during pregnancy (such as eclampsia) and pre-existing hypertensive conditions.

Legacy concepts and concepts with redundant phrasing have been updated as follows:

• Hypertension in obstetric context: The legacy concept 367390009 |Hypertension in the obstetric context (disorder) has been treated as synonymous with maternal hypertension and inactivated as a duplicate of 288250001 |Maternal hypertension (disorder).

• Chronic hypertension in pregnancy: The legacy phrase chronic hypertension in pregnancy is considered equivalent to pre-existing hypertension. Consequently, 8762007 |Chronic hypertension in obstetric context (disorder)| has been inactivated with historical association to a new concept 1373659007 |Pre-existing hypertension during maternal antenatal and/or intrapartum and/or postpartum period (disorder).

During revisions the working definition used for labor dystocia is: an “abnormal” labor progression during the latent (up to 4-6 cm dilation) or active phase (from 4-6 cm until full dilation) of the first stage of labor; or, during the second stage (from complete cervical dilation until delivery of the baby) - this dystocia can be caused by a variety of etiologies including: uterine, pelvic (passage), and fetal origins. Pre-existing hierarchies for 31805001 |Fetal disproportion (disorder)| and 237256006 |Disorder of pelvic size and disproportion (disorder)| have been harmonized with related clinical findings rationalized to align with the following definitions:

• Fetal orientation: the relationship of the fetus to the uterus, cervix, and maternal pelvis.

• Fetal presentation: the part of the fetus occupying the lower pole of the uterus, or presenting to the pelvic inlet, e.g. vertex (cephalic), face, brow, breech, shoulder, funic (umbilical cord), or compound (more than one part, such as shoulder and hand).

• Fetal position: the relation of the presenting part to an anatomic axis e.g. for vertex presentation this may be occipitoanterior, occipitoposterior or occipitotransverse.

The orientation of a fetus may be determined during the pregnancy by palpation, ultrasound, etc., and these are findings, as the presentation, position, and lie are initially changeable until gradually becoming more set as the pregnancy approaches term. It is at the later stages of pregnancy or during labor that the description of the fetus’ orientation relate to a disorder. This can become confusing ontologically. For example, a transverse lie during pregnancy is not uncommon, and although it may be indicative of an associated condition, e.g., placenta previa, it can be a normal variant. Transverse lie at a later stage of pregnancy, such as in labor, has a more significant nuance, because, not only may it be indicative of various conditions causing difficulty for the fetal head to engage, it can also be associated with an increased incidence of other conditions, such as cord prolapse.

Concepts such as |Isoimmunization affecting pregnancy| have been inactivated as ambiguous with historical association to the maternal disorder of the development of isoimmunization secondary to incompatible (paternally-derived) fetal blood group antigens; and, the hemolytic fetal/neonatal impact:

Maternal isoimmunization has a synonym, Maternal alloimmunization. Although alloimmunization is not strictly synonymous with isoimmunization, the terms are closely related and sometimes used interchangeably in clinical practice. Alloimmunization refers to the immune response generated when an individual is exposed to antigens from another member of the same species (allogeneic), leading to the production of antibodies against these foreign antigens. This process commonly occurs after blood transfusion, organ transplantation, or pregnancy, and can involve a wide range of antigens, including red blood cell (RBC) antigens and human leukocyte antigens (HLA). By contrast, isoimmunization is a subset of alloimmunization, specifically describing the immune response against antigens of the same species that are genetically different but of the same type (isoantigens). In clinical usage, isoimmunization most often refers to maternal sensitization to fetal RBC antigens during pregnancy, such as Rh(D) or other blood group antigens, resulting in hemolytic disease of the fetus or newborn. Thus, alloimmunization is a broader term that encompasses isoimmunization, but in the context of incompatible fetal blood group antigens, alloimmunization and Isoimmunization can be used synonymously.

There has also been considerable discussion as to the meaning of the terms typical, atypical, and irregular in the context of maternal alloimmunization to incompatible fetal blood groups. Following expert consultation the following approach has been implemented:

• typical and regular blood group alloimmunization relates to ABO

• irregular blood group alloimmunization relates to non-ABO blood group antigens

As a consequence of this, concepts relating to atypical blood group antibodies have been inactivated, and a single concept 1381698004 |Maternal irregular blood group isoimmunization during antenatal and/or intrapartum period (disorder)| has been retained.

Where injuries are explicitly traumatic and associated with the antenatal or intrapartum period, these are modeled in harmony with other domains using ‘Due to: Traumatic event’.

Concepts with FSNs containing the notion of damage, e.g., 1269255003 |Damage to organ of pelvis due to incomplete miscarriage (disorder)| have been modeled as subtypes of 417163006 |Traumatic or non-traumatic injury (disorder)|. Similarly, for more specific morphologies such as perforation where the etiology is also not necessarily due to a traumatic event, e.g.. 8071005 |Miscarriage with perforation of bowel (disorder), these concepts are also classified as subtypes of 417163006 |Traumatic or non-traumatic injury (disorder)|. By contrast, other specific morphologies, including laceration, e.g., 7809009 |Miscarriage with laceration of uterus (disorder)|, are necessarily traumatic and are modeled with ‘Due to: Traumatic event’.

Concepts temporally relating to trauma and a procedure, e.g., 56451001 |Failed attempted abortion with perforation of broad ligament (disorder)|, are modeled as being ‘Due to: Traumatic event’ and ‘During: Termination of pregnancy (procedure)’.

Where an injury relates to a concept which explicitly states the form of delivery, this has been included in the definition, e.g., 1354495004 |Injury of urethra during vaginal delivery (disorder)| is modeled with ‘Due to: Traumatic event’ and ‘During: 700000006 |Vaginal delivery of fetus (procedure)|’.

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.

The Structure-Entire-Part (SEP) 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.

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.

For more information on part of relationships in the anatomy concept model, please see .

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.

This section contains naming conventions for anatomical structures in SNOMED CT.

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.

Pages in this section:

• Body parts and regions

• 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:

• 11124005 |Atrioventricular valve (body structure)| vs. 279316009 |Atrioventricular (non-mitral, non-tricuspid) valve structure (body structure)|

• 91134007 |Mitral valve structure (body structure)| vs. 312523009 |Left (non-mitral) atrioventricular valve structure (body structure)|

• 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.

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.

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.

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,

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:

421060004 |Structure of vertebral column (body structure)| (synonym: Spinal column, ‘Backbone’, Spine)

• 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).

Similarly, 8454000 |Lumbar spine joint structure (body structure)| subsumes:

• Intervertebral L5-S1 disc

• Structure of lumbosacral joint

• Structure of facet joint between L5 and S1

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)|.

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 clinical situations.

• 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.

• Acquired abnormality of congenital anomaly

• Adverse reaction to X vaccine

• Allergy to X vaccine

• Arrythmia

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)|

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.

Provide Feedback

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.

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.

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.

Provide Feedback

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.

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.

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:

• 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)|

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

See also relative page:

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.

Figure : Stated view of Femoral hernia (disorder)

Respiratory tract

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.

Upper aerodigestive 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 .

Upper respiratory tract

58675001 |Upper respiratory tract structure (body structure)| includes the nasal cavity, paranasal sinuses, nasopharynx, oropharynx, and larynx

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,

• 6553002 |Inferior nasal turbinate structure (body structure)|

• 122491002 |Middle nasal turbinate bone structure (body structure)|

• 65289004 |Superior nasal turbinate structure (body structure)|

• 33415007 |Supreme nasal turbinate structure (body structure)|

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.

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

The genitourinary system includes the entire urinary system, as well as the genital system. The genital system includes internal genital organs and external genitalia.

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)|.

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,

There are two types of abscesses:

1. septic

2. sterile

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.

Provide Feedback

A disorder is always and necessarily an abnormal clinical state.

Disorder modeling information is as follows:

• Specific Clinical finding and Disorder Modeling

• Disorder Combination Modeling

• Complication and Sequela Modeling

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

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)

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?

Order antigens numerically first.

• For example,

  • 732279009 |Cell positive for CD3 antigen and positive for CD4 antigen (cell)|

  • NOT

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)

      • Apoptosis (morphologic abnormality)

      • Morphologically abnormal structure (morphologic abnormality)

      • Structure resulting from tissue repair process (morphologic abnormality)

The concepts in the morphologic abnormality hierarchy represent abnormal body structures.

Choroid

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.

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.

371398005 |Eye region structure (body structure)| has a synonym of orbital region structure which subsumes bony orbit, entire eye, and ocular adnexa.

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 precoordinated concepts; there may be postcoordination 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: .

Observables entities may be used to code headers on a template, elements on a checklist, or to assign values to elements.

< 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.

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,

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.

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)|.

Organism inclusion criteria

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

  • 8745002 | Gram-positive bacterium (organism) |

    • 416983001 | Helical Gram-negative bacillus (organism) |

• For example, a non-Linnaean class of bacteria described by physiology

  • 59343002 | Anaerobic bacteria (organism) |

    • 417454003 | Non-motile Salmonella (organism) |

• For example, A non-Linnaean class of bacteria described by antimicrobial susceptibility

  • 712662001 | Carbapenem resistant Enterobacteriaceae (organism) |

  • 417943000 | Methicillin susceptible Staphylococcus aureus (organism) |

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.

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.

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.

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 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.

|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.

These morphologies with text definitions represent 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)|

• |Deep tissue pressure injury (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 are inactive with targets to 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)|

399912005 |Pressure ulcer (disorder)| is inactive 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 the associated morphology (attribute) changed from 420226006 |Pressure ulcer (morphologic abnormality)| to 1163214006 |Pressure injury (morphologic abnormality)|. This results in these concepts being relocated under |Pressure injury (disorder)|.

When authoring in this domain, these are the approved attributes and allowable ranges.

See also the respective templates.

Domain Information for Body Structure

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.

1. FSN must include the word 'structure', 'entire' or 'part' for concepts that are following the SEP model.

For example,

• Liver structure (body structure)

• Entire liver (body structure)

• Liver part (body structure)

2. All descriptions for Entire concept must contain the word 'Entire'.

For example,

For example,

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).

Templates are available for modeling quality observables and for process observables:

• Simple template for Quality Observable (observable entity) - v2.0

• Simple template for Process Observable (observable entity) - v3.0

  • A nutritional intake (observable entity) - v3.0

• • The Susceptibility template is a disposition observable; there is no simple template at this time.

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

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.

Provide Feedback

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

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)|:

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.

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)

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:

• Occurrence = Congenital (qualifier value).

It may also include:

• Finding site = X (body structure)

• 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)|

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)|.

Congenital absence can represent at least three different classes of absence:

1. Total developmental absence of the affected organ/structure

2. Partial absence of the affected organ/structure

3. 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:

Congenital absence of X

• Associated morphology = Absence (morphologic abnormality)

• Occurrence = Congenital (qualifier value)

• Finding site = Structure of X (body structure)

• Pathological process = Pathological developmental process (qualifier value)

Aplasia

• Associated morphology = Aplasia (morphologic abnormality)

• Occurrence = Congenital (qualifier value)

• Finding site = Structure of X (body structure)

• Pathological process = Pathological developmental process (qualifier value)

Partial absence of X

• Associated morphology = Aplasia (morphologic abnormality) or Transverse deficiency (morphologic abnormality)

• Occurrence = Congenital (qualifier value)

• Finding site = Part of X (body structure)

• Pathological process = Pathological developmental process (qualifier value)

Agenesis of X or Complete absence of X

• Associated morphology = Agenesis (morphologic abnormality)

• Occurrence = Congenital (qualifier value)

• Finding site = Entire X (body structure)

• Pathological process = Pathological developmental process (qualifier value)

• Acquired abnormality of congenital anomaly

• Malformation, deformation, anomaly

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.

A Clinical finding/Disorder concept's fully specified name (FSN) must be specific, though the preferred term (PT) can be a more clinician-friendly, word-order variant.

The FSN must conform to a specific pattern of "Disease of x" where a specific body structure is involved. For the preferred term, end users can choose the desired description that conforms to common clinical usage.

For example,

• FSN: Disease of kidney (disorder)

• PT: Can be either 'Kidney disease' or 'Renal disease'

The use of -opathy is to be used in the preferred term, because the FSN is to be specific and explicit, and there are often various interpretations of -

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:

1. 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.