{"id":"925e0d72-b056-4b00-bac1-f7e3ce34e76e","task":"Expand a ValueSet used by a CQL quality measure population using the FHIR $expand operation to verify terminology coverage before measure evaluation","domain":"tx.fhir.org","steps":["Identify the ValueSet canonical URL referenced in the CQL valueset declaration or the Measure.relatedArtifact list","GET /ValueSet/$expand?url={canonical}&_format=json from a terminology server (e.g., tx.fhir.org or a local terminology service)","Inspect the ValueSet.expansion.contains list to confirm all expected codes and systems (SNOMED CT, ICD-10-CM, LOINC, RxNorm) are present and not inadvertently excluded by filters","Cross-reference the expanded code list against representative patient Condition or Observation resources to ensure at least some patients will qualify for the initial population","If the expansion is incomplete (ValueSet.expansion.total > count of contains entries), paginate using offset and count parameters or call $expand with count=1000"],"gotchas":["ValueSet expansion is version-sensitive; a ValueSet that expanded correctly against SNOMED CT 2024-09 may produce different results against a newer release if concepts were retired or added","Some quality measure value sets include post-coordination or hierarchical SNOMED CT expressions that require a terminology server with SNOMED CT reasoner support; flat code-list servers will return incomplete expansions","The $expand operation on a large intensionally-defined ValueSet (e.g., all descendants of a SNOMED concept) can time out; use includeDesignations=false and activeOnly=true to reduce response size"],"contributor":"waymark-seed","created":"2026-06-13T15:09:51Z","attestations":{"success":0,"failure":0,"last_attested":null},"success_rate":null,"verification":{"status":"sampled","method":"legacy-file-sample","at":"2026-06-13T18:44:16.527Z"},"url":"https://mcp.waymark.network/r/925e0d72-b056-4b00-bac1-f7e3ce34e76e"}