Introduction

Background

SNOMED CT terminology provides a common language that enables a consistent way of indexing, storing, retrieving, and aggregating clinical data across specialties and sites of care.

SNOMED International maintains the SNOMED CT technical design, the content architecture, the SNOMED CT content (includes the concepts table, the descriptions table, the relationships table, a history table, and ICD mappings), and related technical documentation.

Purpose

This document provides a summarized description of the content changes included in the April 2023 release of SNOMED Clinical Terms^® (SCT) International Release.

It also includes technical notes detailing the known content or technical issues where the root cause is understood, the fix has been discussed and agreed to, but has yet to be implemented.

The SNOMED International Release Notes are available alongside the April 2023 International release.

Scope

This document is written for the purpose described above and is not intended to provide details of the technical specifications for SNOMED CT or encompass every change made during the release.

Audience

The audience includes National Release Centers, WHO-FIC release centers, vendors of electronic health records, terminology developers and managers who wish to have an understanding of changes that have been incorporated into the April 2023 International release.

Please note, you may have to register for a Confluence user account in order to access the links included in these release notes.

Content Development Activity

Summary

Continuous quality improvement and enhancement of existing content is an ongoing process undertaken by SNOMED International in preparation for every release. The April 2023 International Release has seen a continuation of the work driven by contributions from: Kaiser Permanente i.e. Convergent Medical Terminology (CMT), Global Medical Device Nomenclature Agency (GMDNA), Orphanet and other domain specific collaborations as well as requests received via the Content Request System (CRS). 

Additionally quality improvement activities are advanced via project driven initiatives summarized below.  Additional work items impacting every release are updates to the SNOMED CT derived maps such as ICD-10 and ICD-O; details are included in these release notes.  

Information about editorial decisions may be found in the SNOMED CT Editorial Guide; mapping guidance for ICD-10 can be found here.

Quality Initiative

The Quality Initiative (QI) project is the implementation of the Quality Strategy. After a successful pilot project for the July 2018 release the next stage has been implemented for subsequent releases including April 2023. 

Quality improvement tasks are being deployed to improve internal structural consistency and ensure compliance with editorial policy related to the stated modeling of content. Additionally, correction or addition of defining relationships is being carried out to accurately reflect current clinical knowledge and ensure the semantic reliability of descriptions associated with a concept. 

 Update of Occurrence for Maternal and Fetal Concepts

Following the creation of new period of life qualifier values to support maternal and fetal periods, concepts representing disorders of the maternal pregnancy, childbirth and puerperium periods as well as fetal disorders have been remodeled to use these new periods of life. Additionally, ambiguous (disjoint) classification-based concepts have been inactivated and replaced with multiple non-ambiguous concepts.

Body Structure 

 SEP and Laterality Anatomy Reference Sets

The release file for the lateralizable body structure reference set has been updated and validated.

The release file for the SEP reference set has been updated and validated.

Clinical Finding

Inactivation of 420079008 |Relapsing fever (disorder)|

420079008 |Relapsing fever (disorder)| has been inactivated as only one species of Borrelia is associated with 14683004 |Louse-borne relapsing fever (disorder)| the others are all types of 10301003 |Tick-borne relapsing fever (disorder)|. A review of descendant concepts was undertaken with content inactivation for ambiguous concepts where the descriptions referred to both the infection and the fever separately and/or included a country or continent based on a specific species of Borrelia.

For example: 

• 43626008 |Relapsing fever of Central AND/OR South Africa (disorder)|, Synonym - Infection by Borrelia duttonii

• This has been inactivated as AMBIGUOUS and POSSIBLY EQUIVALENT to:

• 1279689007 |Relapsing fever caused by Borrelia duttonii (disorder)| OR 1279690003 |Infection caused by Borrelia duttonii (disorder)|

Content in this area has also been updated to include relapsing clinical course.

 Procedure

Inactivation of 103693007 |Diagnostic procedure (procedure)|

Following on from the update for procedure content which stated intent diagnostic undertaken in 2022, the concept 103693007 |Diagnostic procedure (procedure)| has been inactivated. This concept cannot capture all diagnostic procedures given that some procedures do not differentiate between diagnostic or therapeutic and therefore cannot be modeled with intent.

Collaboration/Harmonization Agreements

Convergent Medical Terminology (CMT)

Content addition for this agreement is ongoing.

Orphanet

Working in collaboration with Orphanet (http://www.orpha.net/consor/cgi-bin/index.php), content development is ongoing for rare disease concepts in SNOMED CT. Content in scope for this project is published in the annual update of the SNOMED CT to Orphanet Maps.

All of the concepts added for the Orphanet project have been mapped to ICD-10.

Cancer Synoptic Reporting

Cancer synoptic reports are used by many member countries to record pathology examination of cancer specimens including the College of American Pathologists (US and Canada), Royal College of Pathology (UK), Royal College of Pathology Australasia (Australia, New Zealand), PALGA (The Netherlands), Swedish Society of Pathology, and others.

For more information about this project, please see Cancer Synoptic Reporting Clinical Project Group 

International League Against Epilepsy (ILAE)

In line with approved harmonized terminology, this project is working on alignment including restructuring to update the hierarchy  << 313307000 |Epileptic seizure (finding)|.

Further information about the changes is available here. 

Gravity Project

Five new Gravity project concepts have been added.

Internal Quality Improvement

Machine Readable Concept Model (MRCM) Changes

There have been no changes for the April 2023 release.

Changes that are in progress can be viewed via the MRCM Daily Build Browser

Please see early visibility for future changes to MRCM.

SNOMED CT derived products

ICD-10 map

The SNOMED CT to the International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (© World Health Organization 1994) 2016 Version map (SNOMED CT to ICD-10 Map) is included in the SNOMED CT International release as a Baseline. The SNOMED CT to ICD-10 Map was created to support the epidemiological, statistical and administrative reporting needs of SNOMED International member countries and WHO Collaborating Centers.

The SNOMED CT to ICD-10 Map is released in Release Format 2 (RF2) only. It is located in the file der2_iisssccRefset_ExtendedMapFull_INT_20200731.txt, which is in the Map folder under Refset, in each of the three RF2 Release Type folders. 

The SNOMED CT to ICD-10 Map is released as Refset 447562003 |ICD-10 complex map reference set (foundation metadata concept)|.

The ICD-10 Mapping Technical Guide (including exemplars) is hosted here https://confluence.ihtsdotools.org/display/DOCICD10

2.10.2. Content Development Activity Summary

The map is a directed set of relationships from SNOMED CT source concepts to ICD-10 target classification codes.  The SNOMED CT source domains for the MAP are limited to subtypes of 404684003 |clinical finding|, 272379006 |event| and 243796009 |situation with explicit context|.  The target classification codes are ICD-10 2016 release. 

Mapped content for April 2023

The map provided for the April 2023 release has been updated, and now represents a complete map from SNOMED CT International release to ICD-10 2016 version.

• 537 newly authored concepts have been added and mapped.

• The SNOMED to ICD-O (morphology) map has 6 additional concepts added as a result of the ICD-O 3.2 review or added due to CRS requests. 

We would welcome feedback on any issues that users of the map may detect when using the map. Issues should be submitted via mapping@snomed.org

SNOMED CT to OWL conversion and classification

The repository containing the toolkit enabling simple SNOMED CT to OWL conversion and classification can be found here, including documentation on its use: https://github.com/IHTSDO/snomed-owl-toolkit

Please contact SNOMED International at support@snomed.org if you would like to provide any feedback on ways to extend and improve the new toolkit.