Interface Guide

Using Codes

Many fields in FHIR are represented with coded values. The HL7 FHIR specification outlines several ways to define and use codes in resources. Codes commonly come from:

Resources used in the FHIR Interface may contain any of these coded values. CareEvolution’s internal terminology management system can associate local terms with canonical terms, and will provide that association when available.

For example, consider the following Observation resource. Although there is a custom code of “GLU” from the DemoEMR system, it has been associated with the Glucose LOINC code. This gives you context for the code’s semantic meaning.

        <system value="http://fhir.carevolution.com/codes/DemoEMR/LabObservationType" />
        <code value="GLU" />
        <display value="Glucose" />
        <userSelected value="true" />
        <system value="http://loinc.org" />
        <code value="2345-7" />
        <display value="Glucose SerPl-mCnc" />
        <userSelected value="false" />
    <text value="Glucose" />

Even if no canonical term exists, the “text” field still provides a human-readable representation.