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The official version of the OHIE workflows can be found in the OpenHIE Architecture Specification.


Description: This transaction allows a PoS, or any OHIE component, to access terminological information in the terminology service to retrieve detailed information on a code.  A typical example would be to retrieve descriptive information on a laboratory code from the LOINC Code System. 

Both external systems and systems inside the HIE may perform this transaction directly with the TS.  The sequence diagram below shows the steps that occur for a system using this transaction.   

  1. Lookup: Retrieve information on Code '26453-1' in the LOINC Code System.

Sponsor:  Jack Bowie

Status:  This operation has been extensively tested in FHIR Connectathons. 

Referenced Standards and APIs

  • The FHIR CodeSystem lookup operation: HL7 FHIR Specifications v3.0 or higher support lookup. The response is an object that contains details about the code, including definition, status, designations, and properties.
  • This workflow implements the IHE IT Infrastructure Technical Framework Supplement - Sharing Valuesets, Codes, and Maps (SVCM) Transaction: Lookup Code ITI-Y4.
  • To verify code existence in a Code System, see the Verify Code workflow.

Assumptions and Prerequisites

  • The required CodeSystems have been preloaded into the Terminology Service and the specified code exists in the Code System.


  • PoS - The point-of-service system or other HIE component that is requesting to lookup a code.  
  • TS - Stores the curated official version of the terminology and codes for the health system.  

Technical details

RefInteractionEndpointDataTransaction Specification
1Code lookup requestTS

The lookup request is triggered by a PoS or other HIE component.

Input: A Concept Code and target Code System.

FHIR CodeSystem Resource, $lookup operation
2.Code lookup responsePoS

The response is sent back to the requesting system.

Output: an object containing code information.

 FHIR CodeSystem Resource, $lookup operation