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 September 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 September 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 September 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.

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 September 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 September 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 Ligation of Major Artery of X Procedure Concepts

Concepts referencing - Ligation of major artery of X[Body structure] have been inactivated with new concepts created using the pattern Ligation of artery of X[Body structure) as needed to replace inactivated terms.

Number of concepts edited (approx): 7

2.2.2. Remodel 50465008 |Hernia repair (procedure)| and Subtypes 

50465008 |Hernia repair (procedure)| and subtypes have been reviewed and remodeled for alignment of usage of the 363699004 |Direct device (attribute)| and 424226004 |Using device (attribute)| attributes to current Editorial Guidance.

424226004 |Using device (attribute)| has been used with the 260686004 |Method (attribute)| = << 257903006 |Repair - action (qualifier value)|, because it “refers to the instrument or equipment utilized to execute an action,” and “the device is actually used to carry out the action, that is the focus of the procedure.”

Procedure site 818983003 |Structure of abdominopelvic cavity and/or content of abdominopelvic cavity and/or anterior abdominal wall (body structure)| has been removed from the role group modeled with method 257903006 |Repair - action (qualifier value)| for the generic groupers << 710785000 |Laparoscopic repair of hernia (procedure)| and << 608833000 |Laparoscopic repair of incisional hernia (procedure)| where the site of the procedure is not stated in the descriptions.

363702006 |Has focus (attribute)| has been added to the model when needed for definition of 'repair of hernia' with specific characteristics (e.g. recurrent, strangulated).

257911001 |Repair of recurrence (qualifier value)| has been inactivated.

New disorder concepts related to subtypes of 52515009 |Hernia of abdominal cavity (disorder) | and types of Recurrent hernia have been added.

2.2.3. Inactivation of Intermediate Primitive Groupers

The following two high-level concepts have been inactivated due to vagueness:

• 82832008 |General body state finding (finding)| - primitive with 937 subtypes.
• 365860008 |General clinical state finding (finding)| - defined with 435 subtypes.

2.3.  Body Structure 

2.3.1. Update Hierarchy 34381000 |Anal canal structure (body structure)|

The anatomical hierarchy relating to 34381000 |Anal canal structure (body structure)| has been revised. This update has involved the addition of new concepts and the inactivation of 367605004 |Structure of anal sinus (body structure)| which was a duplicate concept.

The relationship between regions and structures has been improved with adjustments relating to the anal margin; a small number of definitions have also been added. Where the changes have exposed inaccurate modeling in dependant hierarchies - these have been corrected.

Number of concepts edited (approx): 30

2.3.2. Update Hierarchy 34707002 |Structure of biliary tree (body structure)|

The FSN for 34707002|Biliary tract structure (body structure)| has been updated to 34707002 |Structure of biliary tree (body structure)| and the subtypes have been rationalized under 90140006 |Structure of intrahepatic biliary tree (body structure)| and 1340085003 |Structure of extrahepatic biliary tree (body structure)| sub-regions. Some additional concepts have been added to improve the logical organization of the contained class of concepts.

Number of concepts edited (approx): 45

2.3.3. Update Hierarchy 89679009|Mesentery structure (body structure)|

The FSN has been updated from 89679009|Mesentery structure (body structure)| to 89679009 |Structure of mesentery of peritoneum (body structure)|.

The relationship of mesentery and some related concepts have been changed to more accurately reflect their anatomical relationships. Some modeled disorders and procedures have been re-modeled to correct any discrepancies found.

Number of concepts edited (approx): 10

2.3.4. Update Hierarchy 21974007 |Tongue structure (body structure)|

The hierarchy relating to the tongue has been revised to distinguish between some concepts which carry similar terms in common clinical usage, notably the root, base and body of the tongue.

• Some clinicians use ‘root’ to refer to the posterior third of the tongue, and others, to describe a specific deep structure of the anterior two thirds of tongue. To rectify this the preferred term for 47975008 |Structure of root of tongue (body structure)| has been inactivated and referred to 7283002 |Structure of pharyngeal part of tongue (body structure)|.  Text definitions have been added to both concepts.
• The body of tongue is frequently used to refer to the anterior two thirds of tongue that includes the tip – but some users use the term in a more limited way excluding the tip – to resolve this, the concept 61344008|Structure of body of tongue (body structure)| has been given a new FSN 61344008 |Structure of oral part of tongue (body structure)|.
• A new concept 1343492001 |Structure of body of tongue proper (body structure)| has been added accompanied by text definition. 41881006 |Structure of lateral margin of tongue (body structure) and 73041003|Structure of tip of tongue (body structure) have been made subordinate to 24649007 |Structure of border of tongue (body structure).
• Hierarchically, 422005 |Structure of inferior surface of tongue (body structure)| has been changed from being subordinate of 119207006|Tongue part (body structure)| to 787486009 |Structure of inferior part of oral part of tongue (body structure)| with the consequence that disorders of the ventrum of tongue are classified as disorders more specifically of the ‘oral part of tongue’ rather than the ‘tongue’, this is ontologically correct as the ‘pharyngeal part of tongue’ does not have a ventral surface.
• In addition 422005 |Structure of inferior surface of tongue (body structure)| is considered to be equivalent to the “anterior two-thirds of tongue - ventral surface“, and this has exposed two disorder concepts that are duplicates 92794002 |Carcinoma in situ of ventral surface of tongue (disorder)| = 255132007 |Carcinoma in situ of anterior two-thirds of tongue - ventral surface (disorder)|; and 254415008 |Tumor of anterior two-thirds of tongue - ventral surface (disorder)| = 126784003 |Neoplasm of ventral surface of tongue (disorder)|. In addition, as the ventral surface is considered to be subordinate to the inferior part of the oral part of the tongue, this means 275395000 |Carcinoma anterior 2/3 tongue ventrum (disorder)| is superordinate to Carcinoma ventral surface of tongue.
• The junctional zone of the tongue is the boundary between the pharyngeal and oral part of tongue – therefore the concept 23263000 |Structure of junctional zone of dorsum of tongue (body structure)| has been moved to be subordinate of 66938003 |Structure of dorsum of tongue (body structure)| rather than 47975008 |Structure of root of tongue (body structure)| – as a consequence concepts such as 92164002 |Benign neoplasm of junctional zone of tongue (disorder)| are now subordinate to 92078004 |Benign neoplasm of dorsal surface of tongue (disorder) rather than 91990002 |Benign neoplasm of base of tongue (disorder)|.
• 24649007 |Structure of border of tongue (body structure)| has been more accurately located as subordinate to 61344008 |Structure of oral part of tongue (body structure)|, instead of 277006004 |Structure of half of tongue (body structure)| – this is partly because the tip of tongue forms part of the border but is not lateralizable - thus the dependant concept 126783009 |Neoplasm of border of tongue (disorder)| is subordinate to 126785002 |Neoplasm of anterior two-thirds of tongue (disorder)| rather than 126778001 |Neoplasm of tongue (disorder).
• 787485008 |Structure of lateral part of body of tongue (body structure)| has been inactivated with historical association to its duplicate 41881006 |Structure of lateral margin of tongue (body structure)|, resulting in some further inactivations, e.g. 254407005 |Tumor of anterior two-thirds of tongue - lateral margin (disorder)| is inactivated with historical association to 126782004 |Neoplasm of lateral border of tongue (disorder)| - this latter concept is now superordinate to 254410003 |Benign neoplasm of lateral part of body of tongue (disorder)| - the latter concept also being subordinate to 92442000 |Benign neoplasm of border of tongue (disorder)|.
• 2048000 |Lingual tonsil structure (body structure)| is a part of the 245832000 |Structure of mucosa of dorsum of pharyngeal portion of tongue (body structure)| and as a consequence 254423005 |Carcinoma of lingual tonsil (disorder)| has a new association of being subordinate to Carcinoma of tongue base – dorsal surface.
• 1159005 |Structure of frenulum linguae (body structure)| has been more accurately assigned to be subordinate to 245836002 |Structure of mucosa of ventral part of tongue (body structure)|, creating a new association as shown in the dependent hierarchy where 254417000 |Carcinoma of frenum linguae (disorder)| is now subordinate to 275395000 |Carcinoma anterior 2/3 tongue ventrum (disorder).

2.3.5. New Concepts for Lesion of Gastrointestinal Tract

Two new concepts have been added:

• 1345172000 |Subepithelial lesion of gastrointestinal tract (disorder)|
• 1345173005 |Subepithelial lesion of large intestine (disorder)|

Over 180 existing concepts, such as gastrointestinal stromal tumor (GIST), leiomyoma, lipoma, pancreatic rest, neuroendocrine neoplasm, benign lymphangioma, varices of the gastrointestinal tract, have been classified under the new concepts by GCI axioms for lesions of layers of the gastrointestinal wall or particular morphologies of the gastrointestinal tract.

2.3.6. Remodel Subtypes of 10200004 |Liver structure (body structure)|

A revision of hepatectomy, partial and total hepatectomy procedure concepts has been undertaken.

107963000 |Excision of liver (procedure)|, 71273005 |Partial hepatectomy (procedure)|, and 17203000 |Total hepatectomy (procedure)| are fully defined by the proximal primitive procedure and the direct site of liver structure, liver part, and entire liver. The model has enabled consistency and improved classification results. In particular, the remodeling focuses on addressing the missing subconcepts of the incomplete classifications of partial hepatectomy, extended hepatic resection, and partial lobectomy of the liver. 

The anatomy of liver parts has been updated, and new concepts have been added to support the remodeling. The relationships between specific lobes and segments have been updated. 80303005 |Structure of lateral segment of left lobe of liver (body structure)| is a part of 360982003 |Structure of segment of left lobe of liver (body structure)|, and Couinaud hepatic segments 5-8 are part of the 48521005 |Structure of right lobe of liver (body structure)|.

2.3.7. 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. Update Descriptions 1231824009|Non-alcoholic fatty liver disease (disorder)| and Subtypes

The descriptions for concepts in this hierarchy have been updated to reflect recent changes for the classification of steatotic liver disease. The changes have been made to FSN and preferred term with the existing descriptions retained as a synonym:

• 1231824009|Non-alcoholic fatty liver disease (disorder)| updated to MASLD - Metabolic dysfunction- associated steatotic liver disease.
• New concept added for MetALD - Metabolic dysfunction and alcohol associated liver disease.
• 442685003|Nonalcoholic steatohepatitis (disorder)| updated to MASH - Metabolic-dysfunction associated steatohepatitis.
• 722866000|Non-alcoholic fatty liver disease without non-alcoholic steatohepatitis (disorder)| updated to MASL - Metabolic dysfunction-associated steatotic liver.
• 197315008 |Non-alcoholic fatty liver (disorder)| (NAFL) inactivated and replaced by MASL - Metabolic dysfunction-associated steatotic liver.

2.4.2. Update 1295265008 |Diffuse tenosynovial giant cell tumor (disorder)| and Subtypes

The descriptions and finding site values for the subtypes of << 1295265008 |Diffuse tenosynovial giant cell tumor (disorder)| have been reviewed and updated as required.

Fully specified names were updated to Diffuse tenosynovial giant cell tumor of <x> (disorder) with preferred term Diffuse tenosynovial giant cell tumor of <x>.

Synonyms specifying 'Pigmented villonodular synovitis of <x>' have been retained. Descriptions using 'Villonodular synovitis of <x>' have been inactivated with reason outdated.

2.5. Procedure

2.5.1. Radiographic Imaging

Work is progressing for this content tracker for information please see the informational briefing note here.

2.5.2. Update for Gender Confirmation Surgery

A stakeholder group has advised that the inclusion of the term 'gender confirmation' in descriptions is not required, rather the generic procedure is what should be described. This aligns with editorial policy on not including the reason for the procedure. Concepts including this term, together with the concept 870629001 |Excision of bilateral breasts for female to male transsexual (procedure)| have been inactivated and replaced with generic procedure and history concepts.

2.6. Collaboration/Harmonization Agreements

2.6.1. Convergent Medical Terminology (CMT)

91 new concepts have been added. The main focus areas were ophthalmology, oncology and musculoskeletal.

2.6.2. Orphanet

Working in collaboration with Orphanet 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. Work has commenced to annotate content added for the Orphanet project with attribution. 

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

2.6.3. 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 

2.6.4. 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)|.

Changes have been made in the area of focal anatomical epilepsy. This includes the addition of one new concept, the updating of descriptions on current concepts, the addition of definitions and inactivation of outdated concepts. Work in the area is continuing.

Further information about the project is available here

2.6.5. Social Care

39 new concepts have been promoted from national extensions to support the three Social Care project domains.

2.6.6. Nursing

22 nursing procedure concepts have been promoted from a national extension to support international work for the content in this area.

2.7. Internal Quality Improvement

2.7.1. Machine Readable Concept Model (MRCM) Changes

There are no changes for the MRCM in the September 2024 International Edition.

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.

2.7.2. Annotation Reference Set

The addition of content for the Annotations refset was commenced in the July 2024 International Edition release and is ongoing for attribution of text definition to organizations with a collaboration agreement, starting with Inserm Orphanet.

2.8. SNOMED CT derived products

2.8.1. 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

2.8.2. 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 September 2024

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

• 216 newly authored concepts have been added and mapped.

• The SNOMED to ICD-O (morphology) map has 3 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

2.8.3. 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

The addition of content for the Annotations refset was commenced in the July 2024 International Edition release.

3.3.3. Changes to the Annotations Refset format

3.3.4. Changes to the RefsetDescriptor records

.

3.3.5.  Proposal to increase the maximum length of Description Types

Please find below the link to the recent announcement on the proposal to increase the limit of characters allowed in Descriptions:

• https://confluence.ihtsdotools.org/pages/viewpage.action?pageId=238158325

A community consultation has been launched to solicit feedback on a proposal to increase the size limits of SNOMED CT concept descriptions to 4096 from the current limit of 255 characters. While this change does not represent a modification of the existing specification, it could be disruptive to implementers who have coded fixed length limits into their systems.  

Please read the full proposal, along with the latest Q&A blog post which details the proposed change, its potential benefits, the feedback process and timelines, and the issues that may need to be considered in such an update:

• https://confluence.ihtsdotools.org/mag/community-consultations/snomed-international-proposal-to-increase-description-length-limit
• https://www.snomed.org/news/blog%3A-snomed-international-seeks-community-feedback-on-proposed-description-character-limit-increase

As always, SNOMED International greatly appreciates any thoughts or opinions that you would like to raise.  If you would like to provide any feedback, please do so as soon as possible, at the very latest before the deadline on Dec 31, 2024.

3.3.6. 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.