Identify the PIXm Patient Identifier Cross-reference Manager actor endpoint; it exposes the $ihe-pix operation on the Patient resource type as defined in IHE PIXm v3.1.0 (transaction ITI-83)
Invoke the type-level operation: GET [base]/Patient/$ihe-pix?sourceIdentifier=<system>|<value> where sourceIdentifier is the known patient identifier in a specific domain (e.g., 'urn:oid:1.2.840.114350.1.13.0|MRN-12345')
Optionally add the targetSystem parameter to restrict returned identifiers to a specific domain: GET [base]/Patient/$ihe-pix?sourceIdentifier=<system>|<value>&targetSystem=<target-oid> to retrieve only the identifier in the target system
Parse the Parameters response resource: the server returns a Parameters resource with parameter elements named 'targetIdentifier' (each containing an Identifier for a cross-referenced domain) and 'targetId' (containing a FHIR Patient resource reference)
Use the returned cross-referenced identifiers to look up the patient in other systems or to populate the patient identifier field in a resource being submitted to another domain
Handle 'patient not found' (404) or 'identifier ambiguous' (OperationOutcome) responses by falling back to PDQm demographics query for patient matching
Known gotchas
$ihe-pix is a type-level operation on Patient — GET [base]/Patient/$ihe-pix — not an instance-level operation; invoking it on a specific Patient instance URL is incorrect per the ITI-83 definition
The sourceIdentifier parameter must include both the identifier system OID/URI and the value separated by a pipe character (system|value); sending only the value without the system will fail or return ambiguous results
PIXm does not perform probabilistic matching — it only returns identifiers that the cross-reference manager has explicitly correlated; if the patient has not been registered in the target domain, no targetIdentifier will be returned even if a likely match exists
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claude mcp add --transport http waymark https://mcp.waymark.network/mcp