US Core Implementation Guide
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US Core Implementation Guide, published by HL7 International - Cross-Group Projects. This is not an authorized publication; it is the continuous build for version 6.0.0-preview). This version is based on the current content of and changes regularly. See the Directory of published versions


This page lists all the ValueSets, CodeSystems, and ConceptMaps defined as part of the US Core Implementation Guide. For more information on using codes in US Core, see the FHIR Terminology section in the FHIR specification and the Coded Elements section in this guide.

Value Sets

These value sets have been defined for this implementation guide.

Code Systems

See the FHIR terminology section for a complete discussion on code systems and a list of code system names used in FHIR. Most code systems used in this guide are defined in the base FHIR specification. However, the following code systems are unique to this guide and not listed in the base FHIR specification. If a URI is listed here, it SHALL be used in the US Core profiles to identify the code system in preference to any other code system URI.

Code systems published in this IG - Includes US Core defined code systems and externally defined code systems

Externally Published code systems

URI Source Comment OID (for non-FHIR systems) CMS Healthcare Common Procedure Coding System (HCPCS) level II alphanumeric codes 2.16.840.1.113883.6.285 CMS International Classification of Diseases, 10th Revision, Procedure Coding System (ICD-10-PCS) - See ICD-10 PCS Codes for online access to codes for general information purposes. 2.16.840.1.113883.6.4 ADA Code on Dental Procedures and Nomenclature 2.16.840.1.113883.6.13 USPS United States Postal Service Two–Letter State and Possession Abbreviations 2.16.840.1.113883.6.92

Using Value Set Authority Center (VSAC)

This guide links terminology directly to the FHIR® Terminology Service for VSAC Resources (Value Set Authority Center (VSAC) - NIH) where applicable using a RESTful API service for accessing the VSAC value sets and supported code systems.

  • VSAC requires login using your own UMLS API Key to view the value sets. VSAC UMLS Licensing information. (See the screenshots below)
  • The value sets in VSAC are specified using a VSAC value set OID.
  • To view the value set expansion in the VSAC user interface, use:

    GET[VSAC OID]/expansion

    An example of this is shown in the screenshots below.

  • To fetch the FHIR ValueSet resource (in other words, the value set definition), use:


  • To fetch the FHIR ValueSet resource expansion use the FHIR $expand operation:

    GET[VSAC OID]/$expand

For more information, refer to the FHIR Terminology Service for VSAC Resources

For example, the US Core Smoking Status Observation Profile valueCodeableConcept element has a preferred binding to the Smoking Status value set. To access it in VSAC, click on the link to

Figure 1: VSAC link

The reader is redirected to the VSAC login page to enter an API Key (only one login is required per session):

Figure 2: VSAC API-Key Login

After successfully entering the API Key, the value set can be inspected, downloaded, etc., using the VSAC User interface, as shown in the figure below. This FHIR ValueSet resource can also be fetched using the URL, and the FHIR ValueSet expansion using the URL$expand.

Figure 3: VSAC Smoking Status ValueSet