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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

Summary of quality improvement changes 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

In total: 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

2.2.1 Anatomy 

  1. Two new association reference sets have been developed and included in this release. The new refsets will help to identify missing concepts, ensure quality of concept modeling and enable systematic application of naming convention for S, E, and P concepts. refsets represent the associations between anatomy Structure, Entire and Part:

    • Anatomy Structure and Entire Association Reference Set
    • Anatomy Structure and Part Association Reference Set

  2. The Lateralizable Body Structure reference set has been updated in the SNOMED International refset tool as follows:

    • ??????? new refset members added and 5 refset members inactivated for the January 2018 release
  3. New content has been added as required for the development of a new concept model for anatomy, as well  as alignment with other anatomy terminology standards as follows:
    • ??????? new concepts; ??????? are Entire concepts which have been added to ensure the completeness of SEP model. 
    • ??????? (approx.) new lateralized body structures and 
    • ??????? new lateralized procedures and disorders
    • ??????? new enthesis concepts added to support the revision of sub-hierarchy of 23680005|Enthesopathy (disorder)| which were incorrectly modeled by two body structures

2.2.2 Clinical finding

  • Added 2005 new concepts for clinical findings and disorders.
    • 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).
    • Remodel and fully define 63491006|Intermittent claudication (finding) and subtypes

2.2.3 Convergent Medical Terminologies (CMT)

A total of ??????? new concepts were added as follows:

  • CMT Cardiology - 12 concepts
  • CMT Emergency Department - 12 concepts
  • CMT Endocrine - 6 concepts
  • CMT Hematology Oncology - 6 concepts
  • CMT Hx and Family Hx - 82 concepts
  • CMT Injuries - 14 concepts
  • CMT Mental Health - 31 concepts
  • CMT Miscellaneous - 104 concepts
  • CMT Musculoskeletal - 272 concepts
  • CMT Neurology - 2 concepts

  • CMT Obstetrics and Gynecology - 2 concepts
  • CMT Ophthalmology - 52 concepts
  • CMT Orthopedics Extremity Fractures - 2 concepts
  • CMT Pediatrics - 2 concepts
  • CMT Radiology - 66 concepts
  • CMT Top 2500 - 3 concepts

2.2.4 Procedures

  • 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

  • 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).
  • Remodel content 243185007 | Advanced life support (procedure) and subtypes (Content project IHTSDO-691)
  • 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
  •  ??????? new concepts were added to support the mapping of LOINC Parts to SNOMED CT concepts for the LOINC - SNOMED CT Cooperation Project. This included properties, techniques, population of cells, cells, etc.

2.2.7 Morphologic Abnormality

  • ??????? 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

  • ??????? changes were made to terms which used an incorrect case in a Salmonella serovar name. 
  • ??????? changes were made to support Microbiology reporting. The majority of these were new organism concepts.

Of these, ??????? term updates were made in the Organism hierarchy and ??????? term replacements were made in other hierarchies (Procedure, Substance, Product, Disorder).

2.2.10 Pharmaceutical / biologic product

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

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 Procedures

  • Revision of hierarchy 23968004|Colectomy (procedure) and subtypes
  • Laterality requests for diagnostic imaging across MRI, CT, X-ray and ultrasonography and interventional radiology 

2.2.13 Social concept

No significant changes for this release. 

2.2.14 Specimen

  • ??????? 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)

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

  • Odontogram - in anticipation of release the Odontogram Refset in August 2017, all supporting concepts were added following approval at the London meeting of the Dentistry project group

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.

  • ??????? 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):

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:

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