Requisition Identity Snapshot Extension

Canonical	../StructureDefinition/nexus-requisition-identity
Status	draft · 1.26.0
Base	Extension (constraint)
Context	ServiceRequest (element)
Source	FSH · JSON

The patient and clinician identity a laboratory requisition was completed with -- the header of the printed sheet, as it stood when the form was filled in.

Overview

A snapshot, not a lookup. The form reads the record when it opens and owns those values from then on. subject, requester and the resources they reference resolve to what the record says now; this says what the paper said. A reprint is checked against this and nothing else.

It also records corrections. A clinician may correct a value on the form without writing the correction back to the chart. The whole header is stored, not only the changed fields, so a later reader can compare this against the record: the fields that differ are the ones that were overridden.

Every child is a string, including the ones that look typed. birthDate is a string and not a date; sex is a string and not a code; province is a string and not a jurisdiction code. They are transcriptions of boxes on a paper form and are preserved exactly as typed, because a value that failed to parse would be dropped rather than reproduced. Parse them downstream if you need to; do not assume they have been parsed, validated or normalized here.

Only the fields that carry a value are written. An absent child means the form held nothing there. It does not mean the form held a deliberate blank.

Not an identity source. Nothing here was validated, and healthNumber was not checked against a payer. A consumer must not use this extension to identify, match or merge a patient -- ServiceRequest.subject is the identity of record.

At most one, on the order only. A requisition has one printed header, and the snapshot is not echoed onto the DiagnosticReport the requisition eventually produces.