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Inactivation Reason

Association

Description

Ambiguous

“POSSIBLY_EQUIVALENT_TO”

This inactivation reason explicitly states that the inactivated concept is inherently ambiguous but that each of the potential meanings represented by the ambiguous concept is semantically identical to one of the “POSSIBLY_EQUIVALENT_TO” target concepts, whether currently present or could be created in SNOMED CT.

The implication of this definition is that for any given ambiguous concept there must be 2 or more POSSIBLY_EQUIVALENT_TO target concepts.

Guidance

Identify all potential meanings represented in the ambiguous concept
Identify ALL possible meanings that arise from the ambiguity. Identify semantically equivalent SCT concepts where they exist, and create new concepts where they do not exist.
Non or partial synonymous synonyms
Resolve these by inactivation as "Not semantically equivalent component' and the association type of "REFERS_TO" reassigning the description to either an existing concept or if necessary creating a new concept.
Ensure that the synonyms on the inactive concept are represented within the appropriate active concept(s).
Classification concept
If the concept's ambiguity results from a classification disjunction or conjunction, use the inactivation reason of "Classification concept".
Incorrect modeling
Where the modeling of the concept is at variance with the meaning of the FSN, correct the modeling - this advice may change once the QI project has been completed and ECL is widely used.
Additional notes:
1. Identifying true ambiguity rather than lack of specificity or the meaning is "not known" and resolving the full suite of POSSIBLTPOSSIBLY_EQUIVALENT_To target concepts can sometimes be difficult.Share difficult ambiguous inactivations in the internal editor's meetings
2. It is possible that one of the interpretations of the ambiguity gives rise to a concept that is not clinically meaningful. It is still important to create a concept to represent this meaning so that there is full semantic equivalence between the sum of the POSSIBLY_EQUIVALENT_TO targets and the ambiguous concept being inactivated as this is the only way of supporting analysis of historically coded clinical data that may have used the ambiguous concept. As a secondary action, the concept that is not clinically meaningful may then itself be inactivated.

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Ambiguous concept that requires intermediate deprecated inactive concepts

Example 1: Mixed ambiguity

Concept
t 200417002|Breast engorgement in pregnancy, the puerperium or lactation unspecified (finding)|
has three possible meanings

Resolution:

Create 3 new concepts:
- Concept
  t xxxxxxxx|Breast engorgement in pregnancy (finding)|
- Concept
  t yyyyyyyy|Breast engorgement in the puerperium (finding)|
- Concept
  t zzzzzzzz|Breast engorgement during unspecified period of lactation (finding)|
Inactivate
Concept
t 200417002|Breast engorgement in pregnancy, the puerperium or lactation unspecified (finding)|
- POSSIBLY_EQUIVALENT_TO xxxxxxxx Breast engorgement in pregnancy (finding)
- POSSIBLY_EQUIVALENT_TO yyyyyyyy Breast engorgement in the puerperium (finding)
- POSSIBLY_EQUIVALENT_TO zzzzzzzz Breast engorgement during unspecified period of lactation (finding)
Now resolve the deprecated "unspecified" concept:
- inactivate
  Concept
  t zzzzzzzz|Breast engorgement during unspecified period of lactation (finding)|
  with reason for inactivation "Classification Concept"
  - REPLACED_BY
    Concept
    t 49746001|Engorgement of breasts (finding)|

Example 2: Mixed ambiguity with a conjunction:

Concept
t 199779004 |Persistent occipitoposterior or occipitoanterior position - delivered (disorder)|
has 2 possible meanings, neither of which already existed in SNOMED CT at the time of writing, in 2021.

The original meaning of this code dates back to ICD9: it is closely related to D660.3 DEEP TRANSVERSE ARREST AND PERSISTENT OCCIPITOPOSTERIOR POSITION DURING LABOR AND DELIVERY, a subtype within ICD9 of D660 OBSTRUCTED LABOR. This implicit meaning as a form of obstructed labor was also originally also reflected in SNOMED by its classification (back in 2002) as a subtype of 199746004 of
Concept
t 199746004|Obstructed labor (finding)|
. From this archaeology, it becomes clear clearer that the "persistent" adjective in the term relates in fact relates only to the "occipitoposterior presentation" permutation; an occipitoanterior presentation of the fetal head is the obstructed labour normal state of affairs in labour, and so would not usually be labelled as "persistent". That labour was obstructed, whichever the presentation, is unstated within the term original SNOMED and ICD terms but was implicit from the original taxonomy in both ICD and later also in SNOMED.

This leads to the following two possible meanings:
- POSSIBLY_EQUIVALENT_TO xxxxxxxx Obstructed labour despite occipitoanterior presentation and now delivered
- POSSIBLY_EQUIVALENT_TO yyyyyyyy Obstructed labour due to persistent occipitoposterior presentation and now delivered
However, both of these are compound clinical statements that should not be added as active concepts but are required in order to satisfy the requirement to ensure clinically safe reporting of historical data.
In addition, it is necessary to resolve the conjunction that arises from the original concept.

Resolution:

Create 2 new concepts:
- Concept
  t xxxxxxxx|Obstructed labour

due to persistent occipitoposterior

- despite occipitoanterior presentation and now delivered (finding)|
- Concept
  t yyyyyyyy|Obstructed labour due to persistent occipitoposterior presentation and now delivered|
Inactivate
Concept
t 199779004 |Persistent occipitoposterior or occipitoanterior position - delivered (disorder)|
- POSSIBLY_EQUIVALENT_TO xxxxxxxx Obstructed labour despite occipitoanterior presentation and now delivered (disorder)
- POSSIBLY_EQUIVALENT_TO yyyyyyyy Obstructed labour due to persistent occipitoposterior presentation and now delivered (disorder)

Now resolve the 2 conjunctions:
- Inactivate
  Concept
  t xxxxxxxx Persistent occipitoposterior |Obstructed labour despite occipitoanterior presentation and now delivered (disorderfinding)|
  as as a Classification concept
  - PARTIALLY_EQUIVALENT_TO
    Concept
    t 199746004 |Obstructed labour (finding)|
  - PARTIALLY_EQUIVALENT_TO
    Concept
    t 37235006 |Occipitoposterior position (finding)|
  - PARTIALLY_EQUIVALENT_TO
    Concept
    t 236973005 |Delivery procedure (procedure)|
  - PARTIALLY_EQUIVALENT_TO
    Concept
    t 289256000|Mother delivered (finding)|
- inactivate inactivate
  Concept
  t yyyyyyyy|Obstructed labour due to persistent occipitoposterior presentation and now delivered (disorder)|
  as as a Classification concept
  - PARTIALLY_EQUIVALENT_TO
    Concept
    t 31041000119106|Obstructed labour due to deep transverse arrest and persistent occipitoposterior position|
  - PARTIALLY_EQUIVALENT_TO
    Concept
    t 236973005 |Delivery procedure (procedure)|
  - PARTIALLY_EQUIVALENT_TO
    Concept
    t 289256000|Mother delivered (finding)|

Resolving sequences of Historical Associations

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Combinatorial Logic

(A) POSSIBLY_EQUIVALENT_TO (B OR C) and (B) SAME_AS (D) implies A POSSIBLY_EQUIVALENT_TO (C OR D)

(A) POSSIBLY_EQUIVALENT_TO (B OR C) and (B) REPLACED_BY (D) implies (A) POSSIBLY_EQUIVALENT_TO (C OR D)

(A^IntEd) POSSIBLY_EQUIVALENT_TO (B^IntEd OR C^IntEd) and (B^IntEd) MOVED_TO (D^NRC) implies (AIntEdA^IntEd) POSSIBLY_EQUIVALENT_TO (C^IntEd)

(A) POSSIBLY_EQUIVALENT_TO (B OR C) and (B) POSSIBLY_EQUIVALENT_TO (D OR E) implies A POSSIBLY_EQUIVALENT_TO (C OR D OR E)

(A) POSSIBLY_EQUIVALENT_TO (B OR C) and (B) WAS_A (D AND E) implies ((A) POSSIBLY_EQUIVALENT_TO (C) OR (A) WAS_A (D AND E))

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Key

Resolving sequences of Historical Associations