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 December 2023 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 December 2023 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 December 2023 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 December 2023 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). 

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 the next stage has been implemented for subsequent releases including December 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. 

2.2.1.  Update 108290001|Radiation oncology AND/OR radiotherapy (procedure)| and Subtypes

108290001 |Radiation oncology AND/OR radiotherapy (procedure)| and subtypes have been reviewed and remodeled as appropriate to remove 363703001|Has intent (attribute)| = 262202000|Therapeutic intent (qualifier value)|.

363703001|Has intent (attribute)| may be appropriate in some instances to distinguish between diagnostic, palliative, or therapeutic intents of a radiation procedure. 

For further information please see this briefing note.

2.2.2. Inactivation of 84499006 |Chronic inflammation (morphologic abnormality)|

84499006 |Chronic inflammation (morphologic abnormality)| has been inactivated with reason DUPLICATE of concept 409777003 Chronic inflammatory morphology (morphologic abnormality).

Concepts in the disorder hierarchy that have been impacted by this inactivation have been remodeled with 116676008|Associated morphology (attribute)| and value of 409777003 Chronic inflammatory morphology (morphologic abnormality).  Approximately 327 concepts have been remodeled as part of this update which completes this Content Tracker.

2.2.3. Update 128422009|Destruction using electrical energy (procedure)| and Subtypes

128422009 |Destruction using electrical energy (procedure)| and descendants have been remodeled with approximately 217 concepts updated:

• Two new concepts have been added 274071003 |Surgical diathermy (procedure)| and 307284001 |Surgical electrolysis (procedure)|.

• General Concept Inclusion (GCI) added to - 274071003 |Surgical diathermy (procedure)|, 119266004 |Coagulation (procedure)| and 73223003 |Electrocoagulation (procedure)|.

• Reclassification of procedures using 18213006 |Electricity (physical force)| formerly under 128422009 |Destruction using electrical energy (procedure)|.

• Fully Specified Name (FSN) have been updated to align with new model along with updates to descriptions.

The updates have been undertaken for this Content Tracker with future changes planned. This will include review of procedure concepts with descriptions relating to Cauterization, Coagulation, Fulguration, Disseccation performed with physical forces different to Electricity (physical force).

2.2.4. AND/OR in the FSN

Classification derived concepts that are subtypes of 71388002 |Procedure (procedure)|using AND/OR in FSN have been reviewed for inactivation in alignment with Editorial Guidance. As needed, new concepts have been created to substitute inactivated concepts without ambiguity.

Subtypes of 1263452006 |Anesthesia and/or sedation procedure (procedure)| and 108290001 |Radiation oncology AND/OR radiotherapy (procedure)| are under review and will be inactivated or modified only if needed to align with other inactivations.

2.2.5. Inactivation of Classification Derived Procedure Concepts

• 304133001 |Access to internal organ (procedure)|

• 278812006 |Vascular access incision (procedure)|

• 439273002 |Incision of bone without division (procedure)|

The above concepts and subtypes have been reviewed and inactivated as appropriate with reason Classification-derived component.

2.2.6. Remodel of Non-surgical Incision Procedures

Normalization of attributes used for Procedure site direct/indirect, Indirect/direct morphology and Direct/indirect substance has been undertaken for concepts modeled with 260686004 |Method (attribute)|= 129287005 |Incision - action (qualifier value)|.

2.2.7. Update for 'Imaging Guided' Procedure Concepts

Approximately 390 procedure concepts that include “imaging guidance” have been revised to resolve previously inconsistency in the modeling of the imaging guidance relationship group where the procedure involves a device and/or morphology as the object of the action for which imaging guidance is being performed.

In a procedure such as an imaging-guided aspiration of a cyst, the morphology is the direct object of the action of aspiration; conversely, in an imaging-guided insertion of a device into a body structure, the body structure is the indirect object of the action of insertion. However, logically, in such procedures the morphology, device, and/or anatomic structure in/on which the procedure is being performed are all the direct object of the imaging action. Previously, these relationships had not been consistently included or modeled. The Editorial Guidance has been updated to include this change to the model.

2.3.  Body Structure 

2.3.1.  Update 280417000|Structure of spinothalamic tract (body structure)|

280417000|Structure of spinothalamic tract (body structure)| and subtypes have been remodeled to distinguish the segments within the spinal cord and the brainstem. A new concept 1296496008 |Structure of tract of brain (body structure)| has been added along with 1296565002 |Structure of spinoreticular tract (body structure)| and 1296588001 |Structure spinocerebellar tract (body structure)|.

As a result of this update the tracts of the central nervous system are subtypes of 57592002 |Central nervous system tract structure (body structure)|. 

2.3.2. Update Subtypes of 78277001 |Temporal lobe structure (body structure)|

A number of concepts relating to the temporal lobe been reviewed and updated, new concepts have been added along with additional descriptions and minor hierarchical rearrangement.

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 Model and Descriptions for Fetal, Neonatal and Perinatal Jaundice Disorder Concepts

A review of content in this area has been undertaken. The semantic tag for concepts representing “Jaundice due to X” and “Jaundice caused by Y” has been updated from (disorder) to (finding); the model and descriptions have been updated accordingly.

Concepts of the type “Jaundice co-occurrent and due to X” have retained an “IS_A” relationship to X (disorder); the semantic tag is retained as “disorder”.

The "Occurrence" attribute value for perinatal jaundice findings has been updated to 1156671008 |Maternal perinatal period (qualifier value)|. This change is required to reflect the fact that these findings are related to the mother, who has the jaundice, rather than the fetus. 

2.4.2. Remodel 14272003 |Premenstrual swelling (finding)|

14272003 |Premenstrual swelling (finding)| has been remodeled and now infers parent 43498006 |Body fluid retention (finding)| with no reference to reproductive function or female genital structure. Premenstrual swelling is premenstrual symptom but not necessarily an 67809006 |Abnormal female reproductive function (finding)|.

2.5. Situation with Explicit Context

2.5.1. Inactivation of 168123008 |Sample sent for examination (situation)| and Subtypes 

168123008 |Sample sent for examination (situation)| and its approximately 90 descendant concepts have been inactivated as they are out of scope of the international edition of SNOMED CT. This update completes this Content Tracker.

2.6. Foundation Metadata Concept

2.6.1. Annotation Reference Set

Three new concepts have been added for the forthcoming annotation reference sets:

• New annotation attribute

• Additional relationship attribute

• Attribution 

2.7. Collaboration/Harmonization Agreements

2.7.1. Convergent Medical Terminology (CMT)

Work is ongoing for this content area.

2.7.2. Orphanet

Working in collaboration with Orphanet (http://www.orpha.net/consor/cgi-bin/index.php), the additional content development required to expand the map for 2023 is complete.

Collaborative 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.

2.7.3. 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 

2.7.4. 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)|.

For the December 2023 release, changes have been made in the areas of neonatal seizures and seizure related findings. This includes the addition of 13 new concepts, FSN and description updates for one concept and inactivation of one outdated concept. In the area of seizure related finding content, 18 concepts have been inactivated. These changes relate to work undertaken to identify 'other’ seizure content that has not yet been managed under this project. There will be further work in the area of ‘other’ seizures in subsequent releases.

Further information about the changes is available here. 

2.7.5. Gravity Project

Work is ongoing for this content area.

2.8. Internal Quality Improvement

2.8.1. Machine Readable Concept Model (MRCM) Changes

The following change has been made for the December 2023 release:

• MRCM for existing attribute 370132008 |Scale type (attribute)| to include 103392008 |Semi-quantitative (qualifier value)|

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.

2.9. 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 December 2023

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

• 201 newly authored concepts have been added and mapped.

• The SNOMED to ICD-O (morphology) map has 4 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. Configuration file in the RF2 package, containing Release Metadata 

A configuration file ("release_package_information.json") is now included in the International Edition, containing metadata about the Release package itself, including:

• effectiveTime
  

• previouslyPublishedPackage

• languageRefset(s)

• licenceStatement

The metadata will be continually refined going forward, so if you have any ideas about useful information to include please send them to release@snomed.org, along with a business case explaining how the information would benefit stakeholders.  Please be aware that use cases will then be assessed by SNOMED International, and new metadata will only be added for strong business cases.  

3.3.3. Changes to the Identifier file format

In line with the proposals documented here:  https://confluence.ihtsdotools.org/mag/snomed-international-proposal-to-change-the-rf2-identifier-file-specification - the International Edition Release includes the following changes to the format of the Identifier files:

• < identifierSchemeId    alternateIdentifier    effectiveTime    active    moduleId    referencedComponentId           ...to
• > alternateIdentifier    effectiveTime    active    moduleId    identifierSchemeId    referencedComponentId

These improvements were introduced in the September 2023 International Edition release, and will be used in all future International Edition releases until further notice.

3.3.4. 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_20231201.txt
• der2_sscsRefset_MemberAnnotationStringValueSnapshot_INT_20231201.txt

These refset files are empty for the December 2023 release, whilst content is authored in future editing cycles.  However, they will then be populated with Annotations data from one of the 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.  Once the initial batch of Annotations data has been formally published to the community in 2024, it will obviously become far more difficult to alter the structure of the files.  Please, therefore, provide any feedback to SNOMED International at release@snomed.org with “December 2023 International Edition release feedback" in the subject line, by 8th December 2023 at the absolute latest.

3.3.5. Early visibility of impending changes in the upcoming 2023 Monthly International Edition releases

Please see the early visibility page below for details of forthcoming changes:

• https://confluence.ihtsdotools.org/display/RMT/2023+Early+Visibility+Release+Notifications