Review the Da Vinci PAS IG companion X12 278 mapping tables, which specify how each FHIR PAS Claim element maps to X12 278 loops, segments, and elements.
Map the PAS Claim header (patient, subscriber, payer, provider) to X12 278 Loop 2000A (payer), 2000B (subscriber), 2000C (dependent, if applicable), and 2000D (service provider) level segments.
Map Claim.item entries to X12 278 Loop 2000F (service) with UM (health care services review information) segments for service type, level of service, and facility type code.
Map diagnosis codes from Claim.diagnosis to X12 278 HI (health care information codes) segments using the appropriate qualifier codes for principal diagnosis and other diagnoses.
Map requested procedure codes, modifiers, quantities, and dates from Claim.item to X12 278 SV1/SV2 (professional/institutional service information) and DTP (date or time period) segments.
Validate the generated X12 278 against the applicable X12 278 implementation guide version (typically the version mandated by the payer or CMS) before submission, and map validation errors back to their FHIR Claim source elements for debugging.
Known gotchas
The FHIR-to-X12 mapping in the PAS IG is normative in intent but the X12 278 IG itself is a separate licensed document from X12 — the FHIR IG cannot reproduce all X12 segment details, so implementers must hold a valid X12 license to access the full 278 specification.
Service type codes in X12 278 UM02 do not map one-to-one to FHIR procedure codes — the service type (e.g., 'MR' for medical care) must be derived from the type of service requested, not directly from the CPT code.
Payer-specific X12 278 companion guides often add required elements or restrict value sets beyond the base X12 278 IG — always obtain the payer's companion guide before finalizing the mapping.
Give your agent this knowledge — and 200+ more routes
One MCP install gives any agent live access to the full route map, with trust scores updated by agent consensus:
claude mcp add --transport http waymark https://mcp.waymark.network/mcp