External causes can be found within multiple hierarchies including the event, disorder, and situation hierarchies.   The corresponding maps vary according to the hierarchy in which the external causes are found and any other conditions represented within the SNOMED concept.  Below are a few ways external causes may be mapped. 

Exemplar: External cause: #1

Source concepts denoting a condition with an identifiable cause within scope of ICD-10 Chapter XX (20) will be mapped to two target classification codes. The external cause classification will be assigned to the second target record (mapGroup=2).

maps to:

• T30.0 "Burn of unspecified region" mapGroup 1, mapCategoryId="Properly classified", mapRule=TRUE, mapAdvice= "ALWAYS T30.0", Map Target = "T30.0"
• X33 "Victim of lightning" mapGroup 2, mapCategoryId = "Properly classified", mapRule = TRUE. mapAdvice is "ALWAYS X33" and "POSSIBLE REQUIREMENT FOR PLACE OF OCCURRENCE" Map Target = "X33"

Exemplar: External cause: #2

If the external cause or location is not explicit in the SNOMED CT concept, the generic external cause code will not be listed as a target ICD-10 code, as illustrated below.  mapAdvice will be used instead to communicate to the end user the necessity to add an external cause code. 

maps to:

• S02.90 "Fracture of skull and facial bones, part unspecified, closed" mapGroup 1, mapCategoryId="Properly classified", mapRule=TRUE. mapAdvice is "ALWAYS S02.90" and "POSSIBLE REQUIREMENT FOR AN EXTERNAL CAUSE CODE" Map Target = "S02.90" The ICD-10 code X59.0, Exposure to unspecified factor causing fracture will not be listed as a second target ICD-10 code.

Exemplar: External cause: #3

SNOMED CT concepts which are descendants of  will be mapped as either External causes or as Factors influencing health status when these are within the scope of ICD-10. 

maps to:

• W10 "Fall on or from stairs or steps, unspecified place: mapCategoryId="Properly classified", mapRule=TRUE. mapAdvice is "ALWAYS W10" and "POSSIBLE REQUIREMENT FOR PLACE OF OCCURRENCE" and "THIS IS AN EXTERNAL CAUSE CODE FOR USE IN A SECONDARY POSITION" Map Target = "W10"

Exemplar: External cause: #4

maps to:

• X33 "Victim of lightning" mapCategoryId="Properly classified", mapRule=TRUE, mapAdvice="ALWAYS X33", "POSSIBLE REQUIREMENT FOR PLACE OF OCCURRENCE" and "THIS IS AN EXTERNAL CAUSE CODE FOR USE IN A SECONDARY POSITION" Map Target = "X33"