1. Introduction

1.1. 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.

1.2. Purpose

This document provides a summarized description of the content changes included in the March 2024 release of SNOMED Clinical Terms^® (SCT) International Edition.

It also includes 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 March 2024 International Edition.

1.3. 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.

1.4. 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 March 2024 International Edition.

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

1.5. Important Information

2. Content Development Activity

2.1. Summary

Continuous quality improvement and enhancement of existing content is an ongoing process undertaken by SNOMED International in preparation for every release. The March 2024 International Edition 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.

2.2. Quality Initiative

The Quality Initiative (QI) project is the implementation of the Quality Strategy. After a successful pilot project for the July 2018 Edition release, the next stage has been implemented for subsequent releases including March 2024. 

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. 

2.2.1.  Inactivation of Morphologic Abnormality Concepts that Specify 'Congenital'

The following morphologic abnormality concepts have been inactivated:

• 61295008 |Congenital abnormal number (morphologic abnormality)

• 125226006|Congenital malposition, left (morphologic abnormality)|

• 125225005|Congenital malposition, right (morphologic abnormality)|

• 56457002|Congenital atresia (morphologic abnormality)|

• 41086002 |Congenital smallness (morphologic abnormality)|

• 81850003|Congenital sequestration (morphologic abnormality)|

These concepts have been replaced by a new concept that does not specify congenital, this aligns with the Editorial Guide.

Concepts in the clinical finding hierarchy that are modeled with associated morphology that has a value of one of the above concepts have been remodeled using the replacement new concept.

2.2.2. Remodel Procedure Concepts for Decompression Fasciotomy

Concepts related to decompression fasciotomy for compartment syndrome have been remodeled and ambiguous concepts related to the leg have been inactivated.  New anatomy concepts relating to fascia have been added and existing relationships updated to support the remodeling of decompression fasciotomy.

Subregions of wrist have been remodeled and missing relationships have been addressed.

Number of concepts edited (approx): 70

2.3.  Body Structure 

2.3.1.  Update Pelvic Vein

Venous structures of the pelvic region have been rearranged to address missing relationships and improve the assignment of the supertype 816092008|Structure of pelvic cross-sectional segment of trunk (body structure)|. These changes resulted in inferred changes to the classification of 150 concepts in other hierarchies.

The fully specified name of these concepts has been updated from "pelvic vein" to "vein of pelvic region" representing any veins within the pelvic region.

New concepts have been added for deep veins of left/right half of pelvic region.

Number of concepts edited (approx): 51

2.3.2. 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.

2.4. Clinical Finding

2.4.1. Description Update for Joint Inflammation/Arthritis

Member requests have highlighted the need to clearly distinguish between joint inflammation (finding) and arthritis of X joint (disorder). Users noted some concepts had both inflammation and arthritis descriptions on the same concept and for a small number there was also duplication in the finding hierarchy under 298160000 |Inflamed joint (finding)| for example:

• 448589005 |Inflammation of joint of hand (disorder)| had a synonym of "arthritis of hand" and there was also a clinical finding 298165005 |Hand joint inflamed (finding)|

For these instances 448589005 |Inflammation of joint of hand (disorder) has had the arthritis synonym inactivated and the concept moved to the clinical finding hierarchy. A new concept was created for 1303804001 |Arthritis of joint of hand (disorder)|.

38 concepts in total were affected by these changes.

2.5. Qualifier Value

2.5.1. New Concepts for Technique

60 new laboratory technique concepts have been added in the 272394005 |Technique (qualifier value)| subhierarchy.

2.6. SNOMED CT Model Component

2.6.1. Update for 738774007 |Is modification of (attribute)|

The definition of this attribute has been updated to clarify the meaning and to facilitate the creation of specific editorial guidance for assignment of this attribute to the substance concepts, specifically the substances that are used in the definition of medicinal products.

2.7. Collaboration/Harmonization Agreements

2.7.1. Social Care

10 new finding concepts have been promoted from a national extension to support social care for older people. These concepts focus on getting into and out of bed as well as managing risk.

2.7.2. Convergent Medical Terminology (CMT)

105 new concepts plus supporting concepts have been added as required (i.e. anatomy, non lateralized parents), with focus on the injury domain and enteropathic arthritis.

2.7.3. Orphanet

Working in collaboration with Orphanet (http://www.orpha.net/consor/cgi-bin/index.php), efforts are ongoing to update rare disease concepts in SNOMED CT to maintain alignment with Orphanet for 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.

2.7.4. 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 

2.7.5. 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 project is available here

2.7.6. Gravity Project

4 concepts have been promoted from a national extension along with the creation of 6 new concepts in the international edition to support the Gravity work.  The new concepts are in the Clinical finding, Procedure and Observable Entity hierarchies.

2.8. Internal Quality Improvement

2.8.1. Machine Readable Concept Model (MRCM) Changes

No  changes have been made for the March 2024 release.

Future changes that are currently in progress can be viewed via the MRCM Daily Build Browser

Please see early visibility for future planned changes to MRCM.

2.8.2. OWL Axiom Expressions for Annotation Properties

The new annotation properties are represented in the OWL expression axiom refset as follows:

• The 1295447006 |Annotation attribute (attribute)| is correctly represented as subClassOf

  • 01300ccd-d1d7-417d-a70a-f688e72c4d8c 20231201 1 900000000000012004 733073007 1295447006 SubClassOf(:1295447006 :246061005)

• All subconcepts of 1295447006 |Annotation attribute (attribute)| are represented as "SubAnnotationPropertyOf", instead of "subClassOf" as they previously were

  • e6cd65fe-cb81-4db4-9ac4-040dc74fce28 20231201 1 900000000000012004 733073007 1295448001 SubClassOf(:1295448001 :1295447006)

  • 3729ce47-a96e-4dc7-9eff-83c34740c414 20231201 1 900000000000012004 733073007 1295449009 SubClassOf(:1295449009 :1295447006)

These axiom updates are published in the March 2024 International Edition release. The authoring tool has been updated to ensure all new subconcepts of 1295447006 |Annotation attribute (attribute)| are represented as SubAnnotationPropertyOf(). Other tools will be updated to correctly consume the updated syntax. This will be carefully tested and rolled out over the next few months.

2.9. SNOMED CT derived products

2.9.1. 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 Edition 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 |SNOMED CT to ICD-10 extended map (foundation metadata concept).

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

2.9.2. 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 March 2024

The map provided for the March 2024 International Edition has been updated, and now represents a complete map from SNOMED CT International Edition to ICD-10 2016 version.

• 285 newly authored concepts have been added and mapped.

• The SNOMED to ICD-O (morphology) map has no 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

2.9.3. 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.

3. Technical notes

3.1. Known Issues

Known Issues are content or technical issues where the root cause is understood, and the resolution has been discussed and agreed but has yet to be implemented.  This can be due to a number of reasons, from lack of time within the new monthly editing cycles, to the risk of impact to the stability of SNOMED CT if the fix were to be deployed at that stage in the Product lifecycle.  

For the current SNOMED CT International edition, the following Known Issues were identified, and agreed to be resolved in future editing cycles:

3.2. Resolved Issues

Resolved issues are Known Issues which were not fixed as part of the previous release lifecycle, but which have now been resolved in the latest release.  They can also be issues found during testing of the current release, which were resolved before the final deployment of the Production release.  Finally they can be issues which were reported or found during the testing phase, but which have been closed without any action taken.  

The Resolved Issues for the current SNOMED CT International edition can be found here:

3.3. Technical updates

3.3.1. RF2 package format

The RF2 package convention dictates that all relevant files are included, regardless of whether or not there is content to be included in each release.  Therefore, the package contains a mixture of files which contain both header rows and content data, and files that (intentionally) include only header records.  The reason that these "empty" files are included in the package is to draw a clear distinction between:

1. ...files that have been deprecated (and therefore removed from the package completely), due to the content no longer being relevant to RF2 in future releases 

2. ...files that happen to contain no data in this particular release (and are therefore included in the package with just a header record), but are still relevant to RF2, and could therefore contain content in future releases.

This allows users to easily distinguish between the two scenarios, as otherwise if files in option 2 were left out of the package it could be interpreted as an error, rather than an intentional lack of content in that release.

3.3.2. Changes to the International Edition package format

In line with the new implementation of Annotations, two new refsets have been added to the International Edition Release package, from December 2023 onwards:

• der2_scsRefset_ComponentAnnotationStringValueSnapshot_INT_20240101.txt
• der2_sscsRefset_MemberAnnotationStringValueSnapshot_INT_20240101.txt

These refset files are empty for the March 2024 release, whilst content is authored in future editing cycles.  However, they will then be populated with Annotations data from one of the future 2024 International Edition releases onwards (date to be confirmed).  These improvements were introduced in the December 2023 International Edition release, and will be used in all future International Edition releases until further notice.

If you have any feedback on the format of these new files please provide it URGENTLY, as changes can potentially be made now (subject to relevant approvals), before the files are populated. 

3.3.3. Proposed change to the Annotations Refset format

3.3.4. Early visibility of impending changes in the upcoming 2024 Monthly International Edition releases

Please see the early visibility Confluence page for details of forthcoming changes.