Programming Guide

This guide introduces some basic concepts and workflows that will be important as you begin using the API.

Single Patient

All Convert API operations assume the input data represents a single individual.

Standardization/Uplift

While clinical documents follow various specifications (CCDA/CCD/CDA, HL7, FHIR, etc.) there is enough variation across systems/vendors to make it challenging for consumers (both human and machine) to handle them. The Convert API performs a lossless standardization process (“uplift”) to make its outputs more consistent and suitable for downstream processing.

See Understanding Uplift for details on the standardization/uplift process.

Patient Identifiers

The “to FHIR” operations allow you to specify optional patient identifiers. You may specify either or both types of identifiers.

patientID

The optional patientId query parameter provides a unique resource ID for the patient. In the output bundle, this will be used for Patient.id in the resulting resource.

For example, if the parameters are: /convert/v1/cdatofhirr4?patientID=3aa0bfc6-89fa-400c-a0d1-81a303b85591

The output would include:

"resource": {
                "resourceType": "Patient",
                "id": "3aa0bfc6-89fa-400c-a0d1-81a303b85591",
                ...
            }

patientIdentifier and patientIdentifierSystem

The optional patientIdentifier and patientIdentifierSystem query parameters specify a business identifier, such as an MRN or MPI identifier. Both parameters must be specified together.

In the output bundle, these parameters will be used for the first identifier field in the resulting Patient resource. Other identifiers from the original payload are also included as subsequent entries in the identifier list. The patientIdentifierSystem specifies the identifier’s system URI.

For example, if the parameters are: convert/v1/cdatofhirr4?patientidentifier=XYZ123456&patientIdentifierSystem=urn:oid:1...

The output would include:

"resource": {
                "resourceType": "Patient",
                "identifier": [
                  {
                      "use": "usual",
                      "type": {
                          "coding": [
                              {
                                  "system": "http://terminology.hl7.org/CodeSystem/v2-0203",
                                  "code": "MR"
                              }
                          ]
                      },
                      "system": "urn:oid:1.2.840.000.1.13.246.2.7.2.688879.7700",
                      "value": "XYZ123456"
                  },
                ...
            }

Output FHIR R4 Bundles

All of the “to FHIR” operations (including Combine FHIR Bundles) return a FHIR R4 Bundle containing the input data converted into FHIR resources. The bundle will be of type collection.

OperationOutcomes

These bundles include an OperationOutcome resource. An OperationOutcome is a collection of issue elements detailing what was parsed from the input, as well as any problems with the conversion. See Operation Outcomes for details.

Resource IDs

The Convert API will generate unique logical ids for all resources in a FHIR bundle that were converted from the input. Resources within a bundle may refer to other resources within the same bundle.

For example, a HL7-to-FHIR conversion may generate a Patient resource, and some Observation resources that reference back to that patient.

Patient:

      "resourceType": "Patient",
      "id": "202b89d5-8187-4131-9863-deb197954dbc",
                
Observation:
        
      "resourceType": "Observation",
      "id": "2.93e9a8b7befa4345b477717d00d125e5",
      
      "subject": {
        "reference": "Patient/202b89d5-8187-4131-9863-deb197954dbc"
      },

Convert API operations are stateless, and different requests are independent of one another. Submitting the same input information to the API multiple times will result in different logical ID elements being generated for the equivalent input concept. In the example above, that means the Patient and Observation will be assigned a different auto-generated id field each time. Business identifiers are retained if sent in the input data.

Codes/Codings/CodeableConcepts

As part of the conversion process, the Convert API will use the Terminology service to standardize input codes.

FHIR Code elements (such as Patient.gender or Condition.clinicalStatus) represent enumerations with a set of possible values. In these situations, the code in the FHIR bundle will be the equivalent input field translated into an equivalent value in the enumeration. An extension element will be added (e.g., Patient._gender, Condition._clinicalStatus) that contains the input code as sent represented as a Coding. For example:

CDA Patient:

    administrativeGenderCode code="F" codeSystem="ExampleNamespace" codeSystemName="ExampleNamespace" displayName="Female"

FHIR Patient:

    "gender": "female",
    "_gender": {
    extension": [{
        ...
        "coding": [{
          "system": "http://rosetta.careevolution.com/codes/Proprietary.ExampleNamespace/Gender",
          "code": "F",
          "display": "Female",

In addition to the data directly present in the input, CodeableConcepts may have additional codings representing the standardized reference codes from the Terminology API. These added codings can be identified by the userSelected: false property. For more information, see Terminology Uplift.