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)|

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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

• Acquired abnormality of congenital anomaly

• Adverse reaction to X vaccine

• Allergy to X vaccine

• Arrythmia

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.

The term enteritis is broad and commonly refers to inflammation of the intestine, especially the small intestine. However, in some conditions, e.g. phlegmonous enteritis and regional enteritis, the term enteritis refers to any part of the digestive tract.

Thus, all descriptions of enteritis must stipulate the specific body structure that is affected to avoid potential misinterpretations and incorrect modeling.

For example,

• Enteritis of intestine

• Enteritis of small intestine

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Representing null values

The addition of new precoordinated content in the Clinical finding (finding) hierarchy that specifies null values, such as 'not recorded', is unacceptable. There is a use case for recording the reason that data are missing; however, this information should be recorded using a concept from the Qualifier value (qualifier value) subhierarchy rather than a Clinical finding (finding) concept.

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Overview

The following modeling and terming guidelines apply to concepts in the International Release.

Modeling

"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

The following illustrates the stated and inferred view for top level grouper 293104008 |Adverse reaction to vaccine product (disorder)|:

The following illustrates the stated view for top level grouper 219075006 |Adverse reaction to vaccine product containing bacteria antigen (disorder)|:

The following illustrates the inferred view for top level grouper 219075006 |Adverse reaction to vaccine product containing bacteria antigen (disorder)|:

The following illustrates the stated view for single ingredient vaccine 293126009 |Adverse reaction to vaccine product containing Hepatitis A virus antigen (disorder)|:

The following illustrates the inferred view for single ingredient vaccine 293126009 |Adverse reaction to vaccine product containing Hepatitis A virus antigen (disorder)|:

The following illustrates the stated view for multiple ingredient vaccine 293125008 |Adverse reaction to vaccine product containing Measles morbillivirus and Mumps orthorubulavirus and Rubella virus antigens (disorder)|:

The following illustrates the inferred view for multiple ingredient vaccine 293125008 |Adverse reaction to vaccine product containing Measles morbillivirus and Mumps orthorubulavirus and Rubella virus antigens (disorder)|:

Naming and modeling of enzyme deficiencies with genetic and non-genetic etiologies

Enzyme deficiencies may arise from genetic abnormalities or non-genetic mechanisms that reduce the activity or availability of an enzyme.

Where an enzyme deficiency may have either a genetic or non-genetic etiology, the naming pattern Deficiency of <accepted enzyme name> (disorder) shall be used for the FSN of an etiologically unspecified concept.

Where the enzyme deficiency concept specifies a gene-caused etiology, the naming pattern <X> gene-related <Y> deficiency (disorder) shall be used, where X represents the approved gene name in the FSN and the gene symbol in the PT. <Y> represents the affected enzyme accepted name.

Modeling requirements

Where an enzyme deficiency specifies a genetic etiology, the concept must be modeled using the HAS ASSOCIATED GENE attribute, with the value representing the gene responsible for the deficiency.

The HAS ASSOCIATED GENE relationship shall not be added to an etiologically unspecified enzyme deficiency concept solely because a genetic cause is known. The existence of genetic and non-genetic causes must be considered when determining whether the relationship is appropriate.

Example: Uroporphyrinogen decarboxylase deficiency

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

Another example is 1076491000119102 |Nontraumatic complete rupture of muscle or tendon structure of rotator cuff of left shoulder (disorder)|.

If this disorder had the same finding site of |Structure of rotator cuff of left shoulder (body structure)| with two different morphologic abnormalities of |Nontraumatic rupture| and |Complete rupture|, then those two morphologic abnormality concepts can be combined to create a single, primitive, morphologic abnormality concept of |Nontraumatic complete rupture (morphologic abnormality)|. This will prevent modeling with two relationship groups.

Instead of modeling as in this stated view:

Model as shown in this stated view:

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,

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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)|.

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?

Multisystem disorders are often rare conditions. There may be limited information about such disorders, so they should be carefully modeled.

When determining parent concepts:

• A multisystem parent concept should be included.

• Genetic or inherited disorders should be modeled in the same way as other genetic and inherited disorders.

• The manifestations of the disorder must always necessarily be true before assigning the relevant parents.

The concepts in the 1254795002 |Substance withdrawal syndrome (disorder)| subhierarchy are modeled as direct children of 64572001 |Disease (disorder)| and are further defined using Due to and After attributes of | dependance (disorder)|.

For example,

74934004 |Psychoactive substance withdrawal syndrome (disorder) has a stated proximal primitive parent of Disease (disorder) and Due to and After attributes of Psychoactive substance dependence (disorder).

Stated view of 74934004 |Psychoactive substance withdrawal syndrome (disorder)|:

Inferred view of 74934004 |Psychoactive substance withdrawal syndrome (disorder)|:

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.

Pulmonary embolus (PE) refers to obstruction of the pulmonary artery or one of its branches by material (e.g. thrombus, tumor, air, or fat) that originated elsewhere in the body. When modeling embolism disorder concepts with pulmonary in the FSN, the Finding site is 782966009 |Structure of artery of pulmonary circulation (body structure)|.

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

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)

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.

708079007 |Overdose of illicit drug (disorder)| is modeled without a Causative agent because the term "illicit drug" may have differing local interpretations.

Vaccine-related overdose concepts in the Clinical Finding/Disorder hierarchy were inactivated in the January 2020 Release. They were replaced with concepts in the Event hierarchy, see 788094008 |Excessive dose of vaccine administered (event)| and subtypes.

When authoring, determine whether the concept describes an overdose, which is a disorder , or the administration or ingestion of an excessive dose, which is an event.

Ischemic disorders are defined by a morphology of ischemic structural change. This need not be permanent, but it is assumed that all ischemia results in some structural alterations at the molecular level.

Ischemic heart disease includes myocardial infarction, myocardial ischemia (without infarction), angina, and other disorders of the heart that have ischemic structural change (reversible or non-reversible) as a defining characteristic.

Coronary arteriosclerosis can, of course, be present without causing ischemia, so coronary arteriosclerosis is not a subtype of ischemic heart disease.

Likewise, there are causes of myocardial ischemia and infarction other than coronary arteriosclerosis, so ischemic heart disease is not a subtype of coronary arteriosclerosis.

The following applies to the subcategory of 118245000 |Measurement finding (finding)|:

• Detected and Not detected are used in the FSN, PT, and modeling of measurement findings instead of Present , Positive , Absent, and Negative.

  • Existing acceptable descriptions with Present , Positive , Absent, and Negative can remain.

Death is an event, not a disorder.

Sudden cardiac death is a term used in clinical practice. It refers to an arrhythmia that results in sudden loss of cardiac function which, if not quickly reversed, will lead to actual death. The FSN Sudden cardiac death (disorder) is modeled as a subtype of 127337006 |Acute heart disease (disorder)|. It should not be classified as death. Individuals with sudden cardiac death have not necessarily been declared dead and are frequently revived. It is regarded as a subtype of cardiac dysrhythmia.

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,

  • Congenital anomaly of is currently modeled as a structural abnormality but is not the same as C ongenital malformation (structural abnormality due to intrinsically disordered development present at birth). Therefore, it can be regarded as having the more general meaning of structural abnormality present at birth.

When referring to a broad term to denote an intrinsic structural abnormality (e.g., Structural abnormality of fetal bladder) and plan to include 49755003 |Morphologically abnormal structure (morphologic abnormality)| in the model, use the pattern Malformation of fetal X or Congenital malformation of X.

Disorder in remission

< X> disorder in remission concepts require a stated relationship to the appropriate primitive Disorder in remission supertype, in addition to the appropriate supertype for the disorder.

For example,

16270831000119107 |Bulimia nervosa in partial remission (disorder)| has stated parents of 698698008 |Bulimia nervosa in remission (disorder)| and 765207007 |Disorder in partial remission (disorder)|.

Where the primitive supertype for the disorder is |Disease (disorder)|, only the Disorder in remission supertype will be required.

For example,

91856007 |Acute lymphoid leukemia in remission (disorder)| has only one stated parent of 765205004 |Disorder in remission (disorder)|, because a potential supertype of 64572001 |Disease (disorder)| would be unnecessary.

See also relative section:

Mental health

Dependence-related concepts which express the current existence of abuse are acceptable.

• For example,

  • 191816009 |Drug dependence (disorder)|

Dependence-related concepts which express the pattern as either continuous or episodic are not acceptable.

Unacceptable patterns:

• 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:

The terms pneumonia and pneumonitis are often used interchangeably. In SNOMED CT, pneumonia is used for infectious causes, and pneumonitis is used for noninfectious causes.

Pneumonia is a type of pneumonitis, as inflammation is present in both. The distinguishing feature between the two disorders is the presence of infection in pneumonia. Pneumonia has a Pathological process (attribute) of Infectious process (qualifier value); pneumonitis does not.

Morphologic abnormality

The morphologic abnormality for both 233604007 |Pneumonia (disorder)| and 205237003 |Pneumonitis (disorder)| is 409774005 |Inflammatory morphology (morphologic abnormality)|.

The clinically-warranted morphologic abnormality for many subtypes of pneumonia is 707496003 |Inflammation and consolidation (morphologic abnormality)|. Consolidation is a feature of most forms of pneumonia; however, it may not be a feature of all pneumonias, such as atypical pneumonias.

Guidance exception

Content has been added that aligns with the 2025 International Multidisciplinary Classification of the Interstitial Pneumonias with attribution to ERS/ATS - European Respiratory Society/American Thoracic Society. For these concepts, the fully specified term and preferred term align with the classification which uses the term pneumonia instead of pneumonitis, even in the absence of an infectious cause.

Disorders with the suffix "-itis" (e.g., cystitis, prostatitis, tonsillitis, appendicitis) are often infectious as well as inflammatory in nature.

For inflammatory conditions whose FSNs specify an infective cause , the modeling should include:

• |Causative agent (attribute)| with the specified organism

• |Pathological process (attribute)| with the type of infectious process

• |Associated morphology (attribute)| with Inflammatory morphology or subtype

• |Finding site (attribute)| with a body structure when known

For inflammatory conditions whose FSNs do not specify an infective cause, an infectious cause should neither be assumed nor modeled when the FSN does not specify it. The modeling would then exclude a Causative agent and Pathological process and should include only:

• |Associated morphology (attribute)| of Inflammatory morphology or subtype

• |Finding site (attribute)| with a body structure when known

Example of inflammatory and infectious disorder,

441551009 |Inflammation of larynx caused by virus (disorder)| (synonym, Viral laryngitis) includes a |Causative agent (attribute)| of |Virus (organism)| and a |Pathological process (attribute)| of |Infectious process (qualifier value)|.

Example of inflammatory disorder not specified as infectious,

446292002 |Necrotizing inflammation of lymph node (disorder)| (synonym, Necrotizing lymphadenitis) does not specify an infective cause, so it is neither modeled with Causative agent nor Pathological process. The model contains an |Associated morphology (attribute)| and a |Finding site (attribute)|.

|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)|.

Germline chromosomal abnormality co-occurring and causing disorder: 41040004 | Complete trisomy 21 syndrome (disorder)|

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.

Germline nucleotide sequence variant co-occurring and causing disorder: 190905008 | Cystic fibrosis (disorder)|

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 NSV (NCBI structural variant) co-occurring and poly-etiologic : BRAF V600E positive melanoma

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,

• Melanoma with BRAF V600E mutation

Representing two associated findings in a single concept may be convenient for recording; however, the representation of the two notions should be recorded separately.

For example,

• Breast cancer occurring with positive estrogen-receptor assay should be recorded in the information model as two separate concepts

Hematologic, lymphatic

There is more than one meaning of hematologic. A definition based on hematological system _ structure includes hematopoietic and lymphoid structures (including bone marrow, spleen, thymus, lymph nodes, etc), as well as the cellular components of blood. Hematologic neoplasms clearly fit this definition.

A definition based on clinical usage by hematologists is broader. Disorders of hemostasis and thrombosis are often managed by hematologists, but these do not have a common structural overlap with the lymphoid and hematopoietic systems (with the exception of platelets and megakaryocytes). For clarity, hematologic disorder is a navigational concept that is used to define a reference set that includes disorders of blood and blood forming organs, as well as disorders of hemostasis and thrombosis, depending on what is intended.

Hematologic disorders, lymphoid and myeloid neoplasms

Hematologic disorders may refer to disorders of: hematopoietic cell origin; blood forming organs (bone marrow, lymph nodes, spleen, thymus, and other lymph tissues); cellular components of blood; or function of hemostatic and thrombotic systems.

Diseases of the blood forming organs (bone marrow, lymph nodes, etc.) can be defined by any one or a combination of the following:

The morphology (neoplastic diseases, at a minimum, include those morphologies covered by neoplasms in the International Classification of Diseases for Oncology, ICD-O).

For example,

• 118599009 |Hodgkin's disease (disorder)| has 128930002 |Hodgkin lymphoma - category (morphologic abnormality)|. The body site involved (especially specific lymph node groups or skin sites).

For example,

• 400122007 |Primary cutaneous T-cell lymphoma (disorder)| has Finding site, skin structure (body structure)

For some disorders, like T-cell lymphomas, and plasma cell and immunosecretory disorders, it is important to distinguish those defined by morphology, site, or manifestation.

T-cell lymphomas can be subcategorized according to the primary site, a lymph node, the skin, or other extranodal site. This means that a site of lymphoid structure cannot be the defining characteristic of the parent concept T-cell lymphoma. Its defining attribute should be morphology alone.

Plasma cell and immunosecretory disorders (e.g. monoclonal gammopathy, heavy chain disease, Waldenstrom's macroglobulinemia) are defined by their manifestations, i.e. the type of monoclonal protein they secrete. Others (e.g. myeloma, plasmacytoma) are defined by their morphology, regardless of whether or not they are secretory.

Immunosecretory disorders may have a morphology of plasma cell neoplasm , even though no mass has been identified and the monoclonal protein may be the only evidence that there is a clonal neoplasm.

In general, lymphoid and myeloid neoplasms can be modeled with their morphologies, but without a site. Leukemias and myelodysplastic syndromes are modeled with Finding Site, bone marrow structure (body structure).

There is more than one meaning of coagulation. A broad meaning, to stop bleeding, is better described as hemostasis. A more narrow definition, limited to the formation of the fibrin clot, might exclude certain components of hemostasis (e.g the ability to stop hemorrhage through the actions of blood vessels, collagen, endothelial cells, and platelets, in the absence of clotting). Individuals with congenital fibrinogen deficiency cannot form fibrin clots, yet their bodies are able to stop bleeding. Therefore, coagulation disorders are kinds of hemostatic disorders.

Rheumatoid arthritis (RA) is a multisystem, inflammatory, autoimmune disorder; the exact etiology is unknown. RA is a disease primarily of the joints and is clinically known as an 'arthritis' although extra-articular manifestations occur. Extra-articular features include nodules, carditis and pericarditis, vasculitis, lung disorders, and other manifestations.

69896004 |Rheumatoid arthritis (disorder)| remains a primitive concept in SNOMED CT and must be stated as a parent (IS A relationship) for all rheumatoid arthritis concepts.

For example,

201776007 |Rheumatoid arthritis of sacroiliac joint (disorder)|

Example of extra-articular rheumatoid manifestation,

28880005 |Rheumatoid arthritis with carditis (disorder)|

There is a need to represent both traumatic and non-traumatic injuries as well as those in which it is undetermined whether the cause of the injury was due to trauma or not. There are forms of trauma that do not result in structural damage, such as emotional trauma , which are defined as traumatic injuries.

Concepts that do not specify trauma are now modeled with the appropriate morphology concept or <<Damage (morphologic abnormality) but are not necessarily assigned a Due to (attribute) of Traumatic event (event), unless the form of injury can only occur with morphologic trauma. In other words, if a concept refers to an injury, and that injury may occur either through trauma or non-traumatic means (e.g. tumor, ischemia, etc.), then it should be modeled without a Due to (attribute) of |Traumatic event|. If, however, the term does not specify trauma, but the type of injury can only occur as a result of trauma (e.g. open wounds), then these concepts would have the DUE TO attribute added.

Historically, injury concepts have been modeled in SNOMED CT as damage to a body structure, unless specifically stated as non-traumatic. 19130008 |Traumatic abnormality (morphologic abnormality)| has been inactivated effective January 2021 in order to separate mechanism of injury (i.e. trauma) from structure (i.e. damage).

396275006 |Osteoarthritis (disorder)| is primarily a degenerative disease, although recent research has identified an increased role of inflammation as an inciting cause. Because of this, 396275006 |Osteoarthritis (disorder)| should now be modeled with a morphology that represents both the inflammatory and degenerative aspects of the disease, 1343602002 |Degeneration and inflammation (morphologic abnormality)|. According to many authoritative sources, osteoarthritis is now regarded as an inflammatory disease, and is now a subtype of arthritis.

SNOMED International uses a number of primary authoritative sources to guide the definition of concepts. For the disease hierarchy, UpToDate () is used as a primary authoritative source. As of November 2024, according to this site, “In the past, οѕteоаrthritiѕ (ՕΑ) was considered to be simply a degenerative "wear and tear" process and therefore often misnamed as degenerative joint disease. However, the pathogenesis of ՕΑ is much more complex than just wear and tear and the term "οѕteоarthritis," where "-itis" is indicative of an inflammatory process, is indeed correct .” Additional recent academic articles also confirm the inflammatory nature of OA.

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)|:

The life phase of pregnancy is unique in that two actors are participants in the scenario, and modeling must distinguish between the two.

• For example,

  • Fetal tachycardia in antepartum versus Maternal tachycardia in antepartum

Mother and fetus share many time periods, such as antenatal. However, some periods are not shared, as in the case of intrapartum. The mother’s intrapartum period includes stages one, two, and three; the fetus’ intrapartum period includes only stages one and two.

A diagram of the relationships between these periods is shown below:

473010000 |Hypersensitivity condition (finding)| is a primitive concept. It subsumes 473011001 |Allergic condition (finding)| and 609405001 |Non-allergic hypersensitivity condition (finding)|.

473010000 |Hypersensitivity condition (finding)| is a direct descendant of 404684003 |Clinical finding (finding)|.

473011001 |Allergic condition (finding)| and 609405001 |Non-allergic hypersensitivity condition (finding)| are both primitive concepts. Each has three main subhierarchies representing:

• Diseases/disorders: abnormal structures

• Processes: allergic and nonallergic hypersensitivity (pseudoallergic) reactions

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)

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 word tumor has two primary meanings: a mass, regardless of whether it is neoplastic or not; or a neoplastic mass. The term neoplasm is preferred since it is less ambiguous than tumor. The word tumor is acceptable as a synonym but not as a preferred term.

For example,

• 92385005 |Benign neoplasm of small intestine (disorder)|

Previously in SNOMED CT, the hierarchy of 372087000 |Primary malignant neoplasm (disorder)| was defined by using an Associated morphology (attribute) relationship to <<86049000 |Malignant neoplasm, primary (morphologic abnormality)|. 86049000 |Malignant neoplasm, primary (morphologic abnormality)| and 367651003 |Malignant neoplasm of primary, secondary, or uncertain origin (morphologic abnormality)| have been inactivated in the November 2022 release and replaced with 1240414004 |Malignant neoplasm (morphologic abnormality)|.

Primary malignant neoplasm disorders are now defined with a role group combining:

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)|’.

Many disorders can occur in combination within the same patient. Guidance on the modeling and terming of FSNs for disorder combinations aims to achieve consistency. Clinically significant disorder combinations are represented in SNOMED CT by a single concept so that users can document temporal (timing) and causal (cause/effect) relationships between the conditions.

Expressing Associations

To express an association between conditions, one of the following associations is used:

• Simple co-occurrence: two or more conditions have no direct causal or temporal relationship but are found together more often than by random chance

• Causation 1: the cause is another finding or disorder, an event, or procedure

• Causation 2: the cause is a physical force, physical object, organism, or substance

• Temporal association: the timing of the two conditions occur before, during, or after each other

When considering disorder combinations two questions can be asked:

1. Is there a causal relationship?

2. What is the temporal relationship?

The following table provides the possible combinations of answers. It allows authors to assign combination disorders to a corresponding category below, to which the appropriate modeling and FSN construction is applied.

*Note: |Temporally related to (attribute)| and its subtypes Before and During are only approved to model perioperative complications and a limited number of other clinical findings.

FSN: X with Y

Assign each condition as a supertype (or ensure that each participating disorder is present in the ancestor tree following classification).

Use simple co-occurrence for two or more conditions that are strongly associated by means other than causality or a temporal relationship (e.g. a common predisposition) where representing such conditions as separate statements would result in a loss of the associated between the conditions.

For example,

• Named syndromes, such as 398114001 | Ehlers-Danlos syndrome (disorder)|

• Manifestations of systemic disorders, such as 83901003 |Sjögren's syndrome (disorder)|

Do not use simple co-occurrence for those disorders with more than one anatomical site or more than one associated morphology. Those disorders should rather be represented as individual concepts in a medical record.

Correct examples:

· Sinusitis with nasal polyps (disorder)

· Acute bronchitis with bronchiectasis (disorder)

Incorrect examples not to be repeated:

· Psoriasis-eczema overlap condition (disorder)

· Hay fever with asthma (disorder)

Causation 1 applies when the cause is another finding, disorder, event, or procedure

For conditions that are causal, or causal and co-occurring, construct the FSN with due to

• X due to Y

For conditions specified as causal and temporal, construct the FSN with due to and the temporal relationship

• X due to and following Y

• Assign the causal disorder as the target of a Due to relationship

• When modeling only causation, ensure the caused condition is represented in the supertypes and/or axioms

• Ensure the caused condition is represented as a supertype and/or axiom

• Ensure Disease (disorder) or the appropriate intermediate primitive is a supertype

• Assign the procedure as the target of a Due to relationship

• Ensure the caused condition is represented as a supertype and/or axiom

• Assign the event as the target of a Due to relationship

• 735173007 | Shock due to anaphylaxis (disorder)| is an example of a condition caused by a clinical finding/disorder. Because the shock and the anaphylaxis are co-occurring, both conditions are represented in the supertypes and axioms, in addition to the Due to relationship.

• 413532003 | Anemia due to blood loss (disorder)| is an example of a condition caused by a clinical finding/disorder. Because the bleeding could have been controlled and thus not necessarily present, only causation is modeled in this concept. The blood loss/bleeding is not represented as a supertype.

• Neutropenia associated with acquired immunodeficiency syndrome (disorder) - Do not use associated; use only with instead. So, |Neutropenia with acquired immunodeficiency syndrome (disorder)|.

• Dilated cardiomyopathy secondary to granuloma (disorder) - Do not use secondary to; use due to instead. So, |Dilated cardiomyopathy due to granuloma (disorder)|.

Causation 2 applies when ¹the cause is a material entity, and ²the means of exposure/introduction are not significant.

1. A material entity refers to a concept within the Substance, Physical object, Pharmaceutical/biologic product, Physical force, and Organism hierarchies.

2. If the means of exposure/introduction are significant, then the causal factor is represented by a concept from the Event hierarchy, and the concept is modeled as Causation 1.

FSN: X caused by Y

Assign the caused disorder (X) as a supertype, or ensure that the caused disorder is a supertype following classification.

Assign the causal factor (Y) as the value of a Causative agent (attribute).

• Contact dermatitis caused by chemical (disorder)

• Choking due to airway obstruction (finding)

• Coma associated with diabetes mellitus (disorder)

• Laser-induced burn (disorder)

Where X occurs after Y:

• if it is not specified that X is due to Y (although causality is frequently implied), construct the FSN as X following Y

Assign the condition or procedure that occurred first in the patient as the target of an After (attribute) relationship. Assign the condition that occurred second as a supertype (or ensure its presence in the ancestor tree).

Examples:

• 402490007 |Calcinosis following localized fat necrosis (disorder)|

  • The fat necrosis occurred first in the patient, so this concept will have an After (attribute) with a value of Fat necrosis (disorder). The calcinosis occurred secondarily, and thus Calcinosis (disorder) is a supertype of this concept.

• 16055031000119100 |Astigmatism of right eye following operative procedure (disorder)|

Not all disorders occurring in combination should be precoordinated into a single concept. Multiple clinical conditions should not be precoordinated in order to facilitate convenient recording in the medical record, even if the two conditions are often reported together.

• For example,

  • The clinical conditions gastroenteritis and dehydration often occur in combination but require separate resolution, and therefore, are best recorded separately in the medical record as 25374005 |Gastroenteritis (disorder)| and 34095006 |Dehydration (disorder)|.

In general, 47429007 |Associated with (attribute)| should be avoided due to the ambiguity which it conveys and the difficulty in applying this role consistently. Instead, Due to is used when there is a direct causal relationship between the conditions; otherwise, the clinical conditions should be recorded as separate concepts in the medical record.

There are a couple of exceptions when the use of 47429007 |Associated with (attribute)| is appropriate:

• Associated with is used to associate the device with a complication where the device may not be a direct cause.

  • For example, an infection of the tissue surrounding an implanted or inserted device is associated with the device but may not be due to the device itself.

• Involves the propensity of an adverse reaction to a substance to occur (other than hypersensitivity or allergic or non-allergic hypersensitivity).

• Associated with is used to associate the intolerance to the substance.

It must be determined if a disorder is caused either by another disorder or by a material entity. A material entity is a concept found in Substance, Physical object, Pharmaceutical/biologic product, Physical force, or Organism subhierarchies. These subhierarchies are the current range constraints for the Causative agent (attribute) in the Clinical finding domain. For combined disorders where a cause can be either a disorder (eg, alcoholism) or a material entity (eg, alcohol):

Model as due to disorder if it is the indirect cause.

• For example,

  • Megaloblastic anemia due to alcoholism (disorder)

Model as caused by material entity if it is the direct cause.

• For example,

  • Inflammation of pancreas caused by alcohol (disorder)

In modeling concepts related to infectious diseases, a number of considerations need to be taken into account.

1. When the disorder is an infectious disease itself, and the organism is specified, then the concept will be modeled with

   1. |Causative agent (attribute)| with the specified organism

   2. |Pathological process (attribute)| with the type of infectious process

2. Disorders can be modeled with |Due to|, with |After|, or with both |Due to| and |After| relationships to infectious diseases.

• If the focus disorder is itself an infectious disorder, it will also have a |Causative agent| relationship when the organism is specified.

  • For example,

    • |Causative agent| relationship: 721742004 |Otitis media caused by Streptococcus pneumoniae (disorder)|

Generally, when |Causative agent| is used in the concept's modeling, the terming 'caused by' is used in the FSN. Similarly, when |Due to| is used in the concept's modeling, the terming 'due to' is used in the FSN. In some situations, both the |Causative agent| and |Due to| are used in a concept's model, and so the naming may vary based on the situation.

In some cases, the DUE TO takes precedence because of a relationship between the causative agent and the DUE TO disorder.

For example,

|Disorder due to alcohol abuse (disorder)|

In other cases, the DUE TO relationship is used as a means to classify the concept appropriately while the CAUSATIVE AGENT takes precedence.

For example,

1251395000 |Injury of skin caused by class Anthozoa (disorder)|

In this case, the DUE TO represents the "injury" part of the concept and allows classification as a traumatic injury. An alternative, but less appealing FSN would have been |Disorder of skin due to traumatic injury caused by class Anthoza|. So, if the concept FSN specifies a disorder causally associated with another disorder, then use due to in the FSN; if the FSN specifies a disorder causally associated with an agent (organism, physical object, substance, etc.), then use caused by in the FSN.

Exceptions may exist to the above guidance which requires review on a case-by-case basis.

The FSN submitted by a requestor may be used as preferred term even if it does not comply with the above recommended pattern. However, do not use phrases such as secondary to, as a result of, etc., in lieu of due to.

Rather than the naming conventions described above, use the names that are accepted clinical parlance and that represent specific pathophysiologic entities for some combined disorders, as the preferred term.

The stricter rules for FSN construction do not prevent the addition of more familiar connectives in other descriptions, for example with, or associated with.