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© 2020 International Health Terminology Standards Development Organisation.  All rights reserved.  SNOMED CT® was originally created by the College of American Pathologists.

This document forms part of the International Edition release of SNOMED CT® distributed by International Health Terminology Standards Development Organisation, trading as SNOMED International, and is subject to the SNOMED CT® Affiliate License, details of which may be found at

No part of this document may be reproduced or transmitted in any form or by any means, or stored in any kind of retrieval system, except by an Affiliate of SNOMED International in accordance with the SNOMED CT® Affiliate License. Any modification of this document (including without limitation the removal or modification of this notice) is prohibited without the express written permission of SNOMED International.

Any copy of this document that is not obtained directly from SNOMED International [or a Member of SNOMED International] is not controlled by SNOMED International, and may have been modified and may be out of date. Any recipient of this document who has received it by other means is encouraged to obtain a copy directly from SNOMED International [or a Member of SNOMED International. Details of the Members of SNOMED International may be found at].


Page At A Glance

Table Of Contents

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 2018 release of SNOMED Clinical Terms® (SCT) International Release.

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

This document is available alongside the January 2018 International Edition release.

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 during the release.

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 2018 International Edition release.


2 Content Development Activity

2.1 Summary

Continuous quality improvement and enhancement of existing content is ongoing based on requests received via the Content Request System (CRS).

As well, the January 2018 International Release has seen a continuation of the work driven by contributions from: Kaiser Permanente Convergent Medical Terminology (CMT), Global Medical Device Nomenclature Agency (GMDNA), World Health Organization (WHO) ICD-11 Beta and International Classification for Nursing Practice ( ICNP®) to add new content to SNOMED CT.  

Additionally, member-identified priority projects, have driven enhancements in the anatomy hierarchy, while other project-driven changes have resulted in new content additions and enhancements to existing content detailed below.

2.2 Content Quality Improvement

4979 new concepts were added

SCT StatisticsNew concept additions
Body structure (body structure)571
Clinical finding (finding)2005
Event (event)12
Observable entity (observable entity)52
Organism (organism)256
Pharmaceutical / biologic product (product)10
Physical object (physical object)171
Procedure (procedure)911
Qualifier value (qualifier value)420
Record artifact (record artifact)115
SNOMED CT Model Component (metadata)29
Situation with explicit context (situation)91
Social context (social concept)10
Specimen (specimen)35
Staging and scales (staging scale)13
Substance (substance)278

21076 changes were made to existing content

SCT Improvement Statistics to Existing ConceptsNumber
Total number of changes21076
Change to stated concept definition7597
Change to inferred concept definition15635
Change in concept definition status from Primitive to Sufficiently Defined 796
Description change6047
Inactivated concepts781
Inactivated descriptions4102
Reactivated concepts14

2.2.1 Anatomy 

  1. New anatomy concepts: 548
      • 462 new lateralised body structure concepts and nearly 1000 new lateralised findings, disorders and procedures. There are over 5,000 lateralised content in SNOMED CT.
      • 30 new concepts for |mucous membrane of nasal cavity and sinus|, and refined the existing hierarchical relationships.
      • New concepts for transplanted cardiac values and structure of vertebral column and/or spinal cord to support concept modeling from ICD-11 content
  2. Reviewed and updated IS A relationships for 1,255 skin structure concepts according to the new anatomy model.
      • Identified and added 329 new IS A relationships. 
      • Inactivated 136 redundant or incorrect IS A relationships
  3. Updates for SEP refsets and Lateralizable body structure refset
      • 42 changes to the SE refset
      • 4 changes to the SP refset
      • 42 new members for lateralisable body structure refset and 10 inactivations.

2.2.2 Clinical finding

  1. New concepts for clinical findings and disorders: 2005
  2. Work completed on review of hierarchy 84017003 | Bursitis (disorder) with concepts remodeled with primitive parent and changes to relationship groups where required also incorporated review of 128200000|Complex regional pain syndrome (disorder)| and subtypes (Content project IHTSDO-418).
  3. Remodel and fully define 63491006|Intermittent claudication (finding) and subtypes
  4. 7 new laboratory finding concepts added along with 30 changes made to existing laboratory concepts.
  5. Revision of spinal injury content - many concepts were primitives and represented as flat list under 26738009|Spinal cord injury without spinal bone injury (disorder)|. This sub-hierarchy has been reviewed and 85 concepts have been remodeled. Most concepts have been defined based on complete, incomplete injuries and levels. These changes have also addressed the reported duplication issues.
  6. Completed work on 'Suspected - findings / disorders, should be situations' (Content project IHTSDO -772)
  7. Remodel 3238004|Pericarditis (disorder)| and subtypes with primitive parent and changes to relationship groups where required to achieve consistency, approximately 100 concepts were remodeled.
  8. Has definitional manifestation: Work has started on remodelling the concepts that are defined in this way. Any existing |Has definitional manifestation | which has a Finding as a value, may be considered for replacement with Interprets/Has interpretation paired values. Any existing |Has definitional manifestation | which has a Disorder as a value may be considered for replacement with suitable IS A relationship (Content project IHTSDO-451).

2.2.3 Convergent Medical Terminologies (CMT)

  1. A total of 766 new concepts were across 3 domains:
      • CMT Neurology
      • CMT Musculoskeletal
      • CMT Radiology

2.2.4 Procedure Hierarchy

  1. Diagnostic Imaging - approximately 363 new concepts added including:
      • MRI 53
      • CT 38
      • Plain X-ray 15
      • Fluoroscopy 73
      • Imaging guided procedure (various modalities) 102
      • Ultrasonography 82
  2. Work completed on review of hierarchy 23968004|Colectomy (procedure) with inactivation of duplicate content, concepts remodeled with primitive parent and changes to relationship groups where required (Content project IHTSDO-111).
  3. Remodel content 243185007 | Advanced life support (procedure) and subtypes (Content project IHTSDO-691)
  4. Remodel and fully define 180081001|Correction of congenital deformity of hand (procedure)| and its descendants.

2.2.5 Disorders Orphanet ICD-11 Harmonization plan

    • ??????? ICD-11 concepts added from the Mortality and Morbidity Linearization
  • 2.2.6  LOINC

105 new SNOMED CT concepts created for LOINC - SNOMED collaboration project.

2.2.7 Morphologic Abnormality

  • 8 new morphologic abnormality concepts added and then mapped to International Classification of Diseases for Oncology Third Edition (ICD-O First Revision, or ICD-O-3.1) 2011

2.2.8 Observables

  • Renamed ??????? “X detail observables (observable entity)” concepts to “X observable” for clarity and retired 1 “X detail observable” as ambiguous. Retired 1 ambiguous Observable entity grouper concept and 1 related ambiguous Clinical finding concept.

2.2.9 Organisms

  • 236 new organism concepts added.
  • Changes to 29 existing concepts in the organism hierarchy.

2.2.10 Pharmaceutical / biologic product

Added >??????? new descriptions with "medication" where "drug" was already used

Drug model project

For further details on the planned changes in this area, please refer to the Drug Model Working Group Directory section.

Please note, you may have to register for Confluence user account in order to access this project.

Summary of changes

New hierarchies
  • Number (qualifier value) - descendants only
    • Existing concepts updated (n ≈ 20)
    • New concepts created (n ≈ 625)

  • Unit of presentation (unit of presentation) - root concept and descendants
    • New concepts created (n ≈ 50)
New semantic tags
  • |Qualifier value (qualifier value)| hierarchy:
    • unit of presentation

  • |Pharmaceutical / biologic product (product) hierarchy|:
    • medicinal product
    • medicinal product form
    • clinical drug

New attribute types

  • Has basis of strength substance
  • Has presentation strength numerator value
  • Has presentation strength numerator unit
  • Has presentation strength denominator value
  • Has presentation strength denominator unit
Attribute description changes
  • |Has dose form|
    • Existing FSN and Preferred Term were inactivated and replaced with |Has manufactured dose form|
  • Descriptions for ≈ 10 existing concepts that represent groupers base on dose form by site prepared for updated in accordance with new terming guidelines.
  • Concepts were fully defined using proximal primitive modeling pattern.
Medicinal product (MP)
  • Descriptions for ≈ 1300 existing concepts updated in accordance with new terming guidelines, including new "medicinal product" semantic tag 
  • Existing concept IDs, stated parents and definition status were retained
  • Missing |Has active ingredient| attributes were added; errors in existing content were corrected as they were identified
Medicinal product form (MPF)
  • Descriptions for ≈ 1300 existing concepts updated in accordance with new terming guidelines, including new "medicinal product form" semantic tag
  • Existing concept IDs, stated parents and definition status were retained
  • Missing |Has active ingredient| and |Has manufactured dose form| attributes were added; errors in existing content were corrected as they were identified
Clinical drug (CD)
  • Descriptions for ≈ 3000 existing concepts representing oral tablets and oral capsules were updated in accordance with new terming guidelines, including new "clinical drug" semantic tag
  • Existing concept IDs, stated parents and definition status were retained
  • Missing |Has active ingredient| and |Has manufactured dose form| attributes were added
  • New |Has basis of strength substance|, |Has presentation strength numerator value|, |Has presentation strength numerator unit|, |Has presentation strength denominator value|, and |Has presentation strength denominator unit| attributes were added


2.2.11 Physical objects

  • ??????? new device concepts added.

2.2.12 Veterinary Extension

  • 2 concepts were moved from the International release into the veterinary extension.

2.2.13 Social concept

No significant changes for this release. 

2.2.14 Specimen

30 new concepts were added.

2.2.15 Substances

  • Summary of changes:
  1. New hierarchy added with semantic tag: Disposition (disposition) 726711005
  2. New attribute added: Has disposition(attribute) 726542003
  3. Concepts containing disjunctives were inactivated, e.g:

    • Antigen of Neisseria meningitidis A + Y (substance)
    • Butyrylcarnitine + isobutyrylcarnitine (substance)
    • Immunoglobulin A antibody to Bordetella pertussis filamentous hemagglutinin + Bordetella pertussis toxin (substance)

  4. Concepts containing brand names were Inactivated e.g:
    • Horlicks drink (substance)
    • Ovaltine drink (substance)

Release plans, Substance hierarchy

For further details on the planned changes in this area, please refer to the Substances project.

Please note, you may have to register for Confluence user account in order to access this project.

2.2.16 Foundation metadata component

Descriptions that are inactivated in the International Edition will use one of the following four values:

    • | Not semantically equivalent component (foundation metadata concept) | - new concept
    • | Outdated component (foundation metadata concept) |
    • | Erroneous component (foundation metadata concept) |
    • | Non conformance to editorial policy component (foundation metadata concept) | - new concept. 
These values will not be applied retroactively. 

2.3. Internal Quality Improvement

2.3.1 Case significance indicator

In order to align in accordance with the RF2 specification, a technical batch change was made to the case significance value for over 760,000 descriptions.

  • Changed from 900000000000020002|Only initial character case insensitive (core metadata concept)| to 900000000000448009|Entire term case insensitive (core metadata concept)|. 

For further details please refer to the document linked here: IHTSDO-950 Update of case significance assignment following the RF2 specification

2.3.2 OWL axiom reference set

Following the recommendation from Modeling Advisory Group, four new concepts have been added to support the development of OWL axiom reference set:

  • 733073007 |OWL axiom reference set|
  • 733929006 |General concept axiom|
  • 734147008 |OWL ontology header|
  • 734146004 |OWL ontology namespace|

2.3.3 Dentistry Odontogram refset

  1. 63 new concepts added to support Dentistry.
  2. The first production release of the Odontogram Refset was made available in October 2017.

2.3.4 New attributes and values



rangeConstraintDomain constraint
Before<< 71388002 |Procedure (procedure)|

Clinical finding


Component<< 123037004 |Body structure (body structure)| OR << 410607006 |Organism (organism)| OR << 105590001 |Substance (substance)| OR << 123038009 |Specimen (specimen)| OR << 260787004 |Physical object (physical object)| OR << 373873005 |Pharmaceutical / biologic product (product)| OR << 419891008 |Record artifact (record artifact)|

Clinical finding


Due to<< 404684003 |Clinical finding (finding)| OR << 272379006 |Event (event)| OR << 71388002 |Procedure (procedure)|

Clinical finding


During<< 71388002 |Procedure (procedure)|

Clinical finding


During AND/OR after<< 404684003 |Clinical finding (finding)| OR << 71388002 |Procedure (procedure)|

Clinical finding


Finding context<< 410514004 |Finding context value (qualifier value)|Finding with explicit context (situation)
Finding informer<< 420158005 |Performer of method (person)| OR << 419358007 |Subject of record or other provider of history (person)| OR << 444018008 |Person with characteristic related to subject of record (person)|Clinical finding
Has basis of strength substance< 105590001 |Substance (substance)|Pharmaceutical / biologic product (product)
Has disposition< 726711005 |Disposition (disposition)| 


Has interpretation<< 260245000 |Finding values (qualifier value)| OR << 263714004 |Colors (qualifier value)|Clinical finding
Has presentation strength denominator unit< 258666001 |Unit (qualifier value)|Pharmaceutical / biologic product (product)
Has presentation strength denominator value< 260299005 |Number (qualifier value)|Pharmaceutical / biologic product (product)
Has presentation strength numerator unit< 258666001 |Unit (qualifier value)|Pharmaceutical / biologic product (product)
Has presentation strength numerator value< 260299005 |Number (qualifier value)|Pharmaceutical / biologic product (product)
Pathological process263680009 |Autoimmune (qualifier value)| OR << 441862004 |Infectious process (qualifier value)| OR << 472963003 |Hypersensitivity process (qualifier value)| OR << 308490002 |Pathological developmental process (qualifier value)| Clinical finding
Temporally related to<< 404684003 |Clinical finding (finding)| OR << 71388002 |Procedure (procedure)|

Clinical finding


2.4 SNOMED CT derived products

2.4.1 ICD-10 map

The SNOMED CT to the International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (© World Health organisation 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 Centres.

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_20170131.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)|. 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 2018

The map provided for the January 2018 release has been updated, and now represents a complete map from SNOMED CT International release to ICD-10 2016 version.

  • 2209 new concepts added

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


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 capacity within the current editing cycle, 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 Snomed CT January 2018 International edition, the following Known Issues were identified, and agreed to be resolved in the next editing cycle (to be published in January 2018):

Key Summary Description

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 - in this case the January 2018 International Edition.  They can also be issues found during the Alpha and Beta testing of the current release, which were resolved before the final deployment of the associated Member 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 Snomed CT January 2018 International edition can be found here:

Key Summary Description Resolved

3.3 Technical updates

3.3.1  Update to case significance assignment, in line with the RF2 specification

The incorrect assignment of case significance for descriptions has been fixed according to the RF2 specification.  The issue was that the value 900000000000448009 |Entire term case insensitive| had not been used due to the data migration from RF1 and limitation of authoring tools. In fact, a majority of SNOMED CT descriptions should have been ‘Entire term case insensitive’.  These terms can be freely switched to lower or upper case without impact to meaning.  The technical batch changes have therefore been made to the case significance value to address this issue.  For full details please see the document here: IHTSDO-950 Update of case significance assignment following the RF2 specification

3.3.3  RF2 package format

For future reference, the RF2 package convention dictates that it contains all relevant files, regardless of whether or not there is content to be included in each particular release.  Therefore, the package contains a mixture of files which contain both header rows and content data, and also files that are intentionally left blank (including only a header record).  The reason that these files are not removed from 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 this or future releases, and 
  2. ...files that just happen to contain no data in this particular release (and are therefore included in the package but left blank, with only a header record), but are still relevant to RF2, and could therefore potentially contain data in future releases.

This allows users to easily distinguish between files that have purposefully been removed or not, as otherwise if files in option 2 above were left out of the package it could be interpreted as an error, rather than an intentional lack of content in that release.

3.3.8  Early visibility of impending change in the January 2018 International edition

Please see the following page for details of all upcoming changes planned for January 2018 and beyond:  Early Visibility - Planned improvements to upcoming SNOMED International Release packages

NOTE:  To access any of the links in the pdf document, please visit the Release Notes online here:



Final Version




Lesley MacNeil
1.00 Maria Braithwaite
Donna Morgan
Rory Davidson 
Jim Case 





Draft Amendment History








Andrew Atkinson

First draft for review and comment





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