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 January 2025 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 January 2025 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 January 2025 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 January 2025 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 January 2025. 

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. Update Surgical Transplantation Procedures

Work has been undertaken for this content tracker.  A briefing note is available here.

267 concepts from the hierarchy 77465005 |Transplantation (procedure)| have been reviewed excluding approximately 20 eye related procedures which will be reviewed by the Ophthalmology Clinical Reference Group with revision once this review is complete.

Approximately 30 procedure concepts relating to hematopoietic cell transplants (including bone marrow and stem cell procedures) have also been excluded from this review as these concepts are not surgical transplantations.

A transplant procedure may or may not be in the same position as the original organ/structure, and the original organ/structure may or may not remain in situ.

An example is 70536003 |Transplant of kidney (procedure)|.  In most kidney transplants, the recipient’s own kidneys remain in situ, but in some cases the kidney is removed. The new kidney is usually placed in the right iliac fossa (but not always) it can be placed in the left iliac fossa, retroperitoneal area or sometimes within the abdominal cavity. In order to incorporate a variety of scenarios depending on each particular organ and patient, for the transplant procedures the preferred option was to use << 24486003 |Structure of transplant (body structure)| for the target of 405813007 |Procedure site - Direct (attribute)|. A 363701004 |Direct substance (attribute)| relationship was only utilized where it added information (autograft, allograft etc).

Following discussion with the Editorial Advisory Group, at the tissue transplant level 'graft' and 'transplant' are used interchangeably so where both concepts existed these were duplicates. Therefore, the tissue transplant procedures have been inactivated and the description placed as a synonym on a new or existing grafting procedure concept. Very high level groupers in the hierarchy have also been inactivated. In total 100 concepts have been inactivated as part of this QI project.

Number of concepts edited (approx): 200

2.3. Body Structure 

2.3.1. Inactivation 421235005 |Structure of femur (body structure)

421235005 |Structure of femur (body structure)| has been inactivated as a duplicate to 71341001 |Bone structure of femur (body structure)|. The modeling has been updated for over 50 diseases and procedures.

The synonym "bone structure of tibia and/or fibula" has been added to 702468001|Bone structure of lower leg (body structure)|.

Number of concepts edited (approx): 80

2.3.2. ​Update 42575006 |Structure of pituitary fossa (body structure) and 1356805000 |Structure of sella turcica (body structure)

The pituitary fossa is part of the sella turcica. A new concept for 1356805000 |Structure of sella turcica (body structure)| has been added and the incorrect synonym on 42575006 |Structure of pituitary fossa (body structure)| has been inactivated. The other parts of the sella turcica have also been rearranged. The procedures and findings related to both pituitary fossa and sella turcica have been reviewed and updated.

Bone structures of regions of the cranial fossa have been removed from the fossa of the cranial cavity because they are material entities and should not be part of an immaterial entity of the cavity.

Number of concepts edited (approx): 30

2.3.3. 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 Hierarchy 118240005 |Finding by method (finding)

Descendants of 118240005 |Finding by method (finding)| have been reviewed to check that 418775008 |Finding method (attribute)| is appropriately grouped with other attributes.

Number of concepts edited (approx): 400

2.4.2. Update 365921005 | Weight change finding (finding) Hierarchy

As a result of multiple requests from member countries regarding overlap and ambiguity for content in this hierarchy, the Nutrition and Dietetics Clinical Reference Group (CRG) conducted a systematic review. The requests had highlighted confusion over similar and overlapping concepts, such as:

• 89362005 | Weight loss (finding)

• 262285001 | Weight decreased (finding)

• 161832001 | Weight decreasing (finding)

• 426977000 | Recent weight loss (finding)

The following changes have been implemented:

• Inactivation of 426977000 | Recent weight loss (finding) | and 427572007 | Recent weight gain (finding)
  These concepts are considered ambiguous due to the subjective nature of the word "recent."

• Inactivation of 161832001 | Weight decreasing (finding) | and 161831008 | Weight increasing (finding)
  These concepts have been inactivated because they do not align with editorial policy. They represent patterns or trends better handled by information models or statistical tools for data interpretation and analysis.

• Inactivation of 89362005 | Weight loss (finding)
  This concept has been identified as a duplicate of 262285001 | Weight decreased (finding). The term "Weight loss," however, has been retained as a synonym for 262285001.

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 Hierarchy 79486002|Oversewing (procedure)|

Oversewing is a technique of suturing. The concept 79486002 |Oversewing (procedure)| should be classified under 18557009 |Closure by suture (procedure)|. It should also be modeled using a surgical suture device. 129360008 |Oversewing - action (qualifier value)| has been moved to be a subtype of 129357001 |Closure - action (qualifier value)|.

Concepts with a description of oversewing have been reviewed and remodeled. For example, oversewing is used as a synonym for closure procedure however that may not be correct because closure could be achieved by other means, e.g. tape, staple, etc. New concepts have been created to address the incorrect synonyms. The classification results have been improved for oversewing procedures. Previously there were three subconcepts for 79486002 |Oversewing (procedure)|, however after this revision the concept now has 17 descendants.

The model for 20 concepts relating to 'closure of perforation' or 'perforated ulcer of X body region' have also been updated to include direct morphology of perforation or perforated ulcer.

Number of concepts edited (approx): 55

2.5.3. Restructure of 384760004 | Feeding and dietary regime (regime/therapy)

Following a review by the Nutrition and Dietetics Clinical Reference Group (CRG), in consultation with the Nursing CRG, a restructuring of this hierarchy has been completed. The content has been reorganized to improve logic, identify and address duplicate concepts (e.g., 414096000 | Enteral hyperalimentation (regime/therapy) | and 229912004 | Enteral feeding (regime/therapy) |) and remove outdated content (e.g., 37041007 | Forced feeding of patient (regime/therapy) |). Where possible, content has been sufficiently defined.

Additionally, the top-level grouper concept 384760004 | Feeding and dietary regime (regime/therapy) | has been inactivated due to its ambiguity, as it was unclear what a combined regime would represent or what the logical subtypes would be. A diagram of the hierarchy following these changes is available in the Early Visibility Notification here.

2.6. Physical Object

2.6.1. Update 272185007 |Meters (physical object)| and Descendants

To support the addition of Gravity provision of device finding content, content improvements have been made to 272185007 |Meters (physical object)| and descendants.

2.7. Collaboration/Harmonization Agreements

2.7.1. Convergent Medical Terminology (CMT)

74 CMT concepts have been added, predominately in the injury and musculoskeletal domains.

2.7.2. 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 to Inserm Orphanet. As part of this effort, textual definitions for concepts previously added for the Orphanet project will be updated to align with the current published version of the Orphanet definition. This will result in published text definitions being inactivated and replaced in bulk. Timelines for publication of these changes can be found in the Early Visibility Release Notifications

NOTE: New annotation that were missing the 'languageDialectCode' have been updated to include 'EN' (approximately 130 concepts).  New validation will be added to enforce the addition of 'languageDialectCode' for new annotation at the time of addition.

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

2.7.3. Gravity

15 new concepts have been added to support the Gravity Project work with a focus on provision procedures and energy poverty findings.

2.7.4. American Joint Committee on Cancer (AJCC) and Union for International Cancer Control (UICC) Staging System 

For 1222584008 |American Joint Committee on Cancer allowable value (qualifier value)| and its 584 descendants the following changes have been made:

• Preferred Term (PT) inactivated and a new PT added that contains the existing AJCC code with a new parenthetical addition of AJCC: (AJCC).
• The existing text definition that contains the attribution to the AJCC Cancer Staging System, American College of Surgeons inactivated and recreated as an annotation.

As a separate hierarchy, approximately 596 new concepts for the Union for International Cancer Control (UICC) TNM staging system have been added. This work has been undertaken for a collaboration agreement between SNOMED International and the UICC.

Hierarchy: qualifier value

Number of concepts edited (approx): 1160

2.7.5. 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 

2.7.6. 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

2.8. Internal Quality Improvement

2.8.1. Machine Readable Concept Model (MRCM) Changes

There are no changes for the MRCM in the January 2025 International Edition.

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

Please see Early Visibility Release Notifications for future planned changes to MRCM.

NOTE: Two planned changes scheduled for the February 2025 International Edition release.

2.8.2. 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.  

NOTE: New annotation that were missing the 'languageDialectCode' have been updated to include 'EN' (approximately 130 concepts).  New validation will be added to enforce the addition of 'languageDialectCode' for new annotation at the time of addition..

2.8.3. Update Concept Non Current Indicators

Concept Non Current (CNC) indicators are a type of inactivation indicator that are applied to active descriptions, when the concept they are attached to is made inactive. They are intended to allow implementers to show some visual cue to alert users that a description they have searched for relates to an inactive concept.

A bulk update has been implemented to inactivate CNC indicators where they are no longer required either because:

• The concept has since been re-activated or,
• The description itself has now been inactivated

This has resulted in a change to approximately 30,000 descriptions for the International Edition release for January 2025.

2.8.4. Bulk Update Case Significance

A bulk update has been implemented to resolve a report of incorrect case significance settings in the International Edition relating to descriptions which include the words; Doppler, Brugada, Bevan, Varicella, Vaccinia, Hepatitis, Genus and more. 

Validation is currently under review and changes will be implemented to prevent future inconsistencies in case significance.

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 January 2025

The map provided for the January 2025 International Edition has been updated, and now represents a complete map from SNOMED CT International Edition to ICD-10 2016 version.

• 297 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 Annotations Refset format

3.3.3. Changes to the RefsetDescriptor records

3.3.4.  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 was 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 appreciated all feedback provided before the deadline (which was Dec 31, 2024).  A summary of the feedback will be collated and disseminated in 2025, alongside a plan for the transition.

3.3.5. Early visibility of impending changes in the upcoming 2025 Monthly International Edition releases

Please see the Early Visibility Release Notifications Confluence page for details of forthcoming changes.