CodeSystem

Overview

The CodeSystem resource represents a code system, which is a set of codes and their meanings. Code systems provide the vocabulary used in coded elements across FHIR resources.

FHIR R4 Specification

See the official HL7 specification: https://hl7.org/fhir/R4/codesystem.html

Supported Fields

Field	Type	Description
id	string	Logical ID of the resource
meta	Meta	Resource metadata
url	uri	Canonical identifier
identifier	Identifier[]	Business identifiers
version	string	Version
name	string	Computer-friendly name
title	string	Human-friendly name
status	code	draft, active, retired, unknown
experimental	boolean	For testing purposes
date	dateTime	Publication date
publisher	string	Publisher name
contact	ContactDetail[]	Contact details
description	markdown	Natural language description
useContext	UsageContext[]	Usage context
jurisdiction	CodeableConcept[]	Intended jurisdiction
purpose	markdown	Why defined
copyright	markdown	Copyright information
caseSensitive	boolean	Case sensitive codes
valueSet	canonical	Value set with all codes
hierarchyMeaning	code	How hierarchy is interpreted
compositional	boolean	Supports post-coordination
versionNeeded	boolean	Version in code display
content	code	not-present, example, fragment, complete, supplement
supplements	canonical	CodeSystem this supplements
count	unsignedInt	Total concept count
filter	BackboneElement[]	Filter properties
property	BackboneElement[]	Additional properties
concept	BackboneElement[]	Concepts in the code system

Search Parameters

Parameter	Type	Description	Example
_id	token	Resource ID	_id=cs-001
identifier	token	Business identifier	identifier=http://example.org/cs
url	uri	Canonical URL	url=http://snomed.info/sct
version	token	Version	version=1.0.0
name	string	Computer name	name=SNOMEDCT
title	string	Human name	title=SNOMED CT
status	token	Publication status	status=active
publisher	string	Publisher	publisher=IHTSDO
description	string	Description	description=clinical
code	token	Code in system	code=386661006
content-mode	token	Content type	content-mode=complete
system	uri	System URL	system=http://snomed.info/sct

Examples

Create a CodeSystem

curl -X POST http://localhost:8080/baseR4/CodeSystem \
  -H "Content-Type: application/fhir+json" \
  -d '{
    "resourceType": "CodeSystem",
    "url": "http://example.org/fhir/CodeSystem/priority-codes",
    "version": "1.0.0",
    "name": "PriorityCodes",
    "title": "Priority Codes",
    "status": "active",
    "experimental": false,
    "date": "2024-01-01",
    "publisher": "Example Organization",
    "description": "Priority levels for clinical tasks",
    "caseSensitive": true,
    "content": "complete",
    "count": 4,
    "concept": [
      {
        "code": "stat",
        "display": "STAT",
        "definition": "Immediate priority, requiring action right away"
      },
      {
        "code": "urgent",
        "display": "Urgent",
        "definition": "High priority, requiring action soon"
      },
      {
        "code": "routine",
        "display": "Routine",
        "definition": "Normal priority"
      },
      {
        "code": "elective",
        "display": "Elective",
        "definition": "Low priority, can be scheduled"
      }
    ]
  }'

Search CodeSystems

# By URL
curl "http://localhost:8080/baseR4/CodeSystem?url=http://example.org/fhir/CodeSystem/priority-codes"

# By status
curl "http://localhost:8080/baseR4/CodeSystem?status=active"

# By name
curl "http://localhost:8080/baseR4/CodeSystem?name=PriorityCodes"

# By content mode
curl "http://localhost:8080/baseR4/CodeSystem?content-mode=complete"

Lookup Code

# Lookup a code in a code system
curl "http://localhost:8080/baseR4/CodeSystem/$lookup?system=http://snomed.info/sct&code=386661006"

Status Codes

Code	Display
draft	Draft
active	Active
retired	Retired
unknown	Unknown

Content Modes

Code	Display	Description
not-present	Not Present	Content not included
example	Example	Only example codes
fragment	Fragment	Partial content
complete	Complete	All codes included
supplement	Supplement	Supplements another system

Common Code Systems

URL	Name
http://snomed.info/sct	SNOMED CT
http://loinc.org	LOINC
http://hl7.org/fhir/sid/icd-10	ICD-10
http://www.ama-assn.org/go/cpt	CPT
http://www.nlm.nih.gov/research/umls/rxnorm	RxNorm
http://unitsofmeasure.org	UCUM