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Inactivation ReasonAssociationDescription

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 POSSIBLT_EQUIVALENT_To target concepts can sometimes be difficult.
    2. Share difficult ambiguous inactivations in the internal editor's meetings
    3. 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.

Examples

Inherently ambiguous FSN with multiple meanings

Multiple possible meanings:

Resolution:

Inherently ambiguous FSN but not all replacement concepts exist

Two possible meanings:

       69878008 | Polycystic ovaries (disorder)|  has 2 possible meanings one of which does not exist within SNOMED CT:

Resolution:

Ambiguous concept that requires intermediate deprecated inactive concepts

Mixed ambiguity with a conjunction:

  • 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 of D660 OBSTRUCTED LABOR. This meaning was also originally reflected in SNOMED by its classification (back in 2002) as a subtype of 199746004 Obstructed labor (finding). From this archaeology, it becomes clear the "persistent" adjective in fact relates only to the "occipitoposterior presentation" permutation; the obstructed labour is unstated within the term but was implicit from the original taxonomy in both ICD and later 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:

  xxxxxxxx | Obstructed labour despite occipitoanterior presentation and now delivered (finding)|

  yyyyyyyy | Obstructed labour due to persistent occipitoposterior presentation and now delivered|

Resolving sequences of Historical Associations

The intention is that functionality to resolve sequences of Historical Associations will normally be seamlessly integrated into the tooling so as to present to the user the appropriate updated historically association to be allocated.

Whenever an already stated POSSIBLY_EQUIVALENT_TO target itself also becomes inactive - whether at the same release or later - identifying the new active, direct replacement(s) for the original inactive concept should follow the combinatorial logic stated below.

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)

(AIntEd) POSSIBLY_EQUIVALENT_TO (BIntEd OR CIntEd) and (BIntEd) MOVED_TO (DNRC) implies (AIntEd) POSSIBLY_EQUIVALENT_TO (CIntEd)

(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))

Note: Once MOVED_TO the NRC we (SNOMED International) have no knowledge of what has happened to BIntEd





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