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 July 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 July 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 July 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). A review of the pre-coordination patterns that are blocking CRS tickets from progressing has commenced and will continue into 2018.

A review of requests currently in the 'In Inception' status in the CRS tool is underway and where it is feasible to progress a request prior to resolving the tracker issue, the request is being identified for progression. Given this work (and the pre-coordination patterns review) the number of requests in 'In Inception' status has decreased by over 1000. This work will continue into 2018.

The July 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

A total of 6494 new concepts were added

A total of 32889 changes were made to existing content

2.2.1 Anatomy 

New anatomy concepts: 357

1. • • 54 new body structure concepts. 
     • 276 new lateralized body structure concepts.
     • There are now over 5,600 lateralized concepts in SNOMED CT and over 300 concepts are new lateralized findings, disorders and procedures.

Updates have been made to 109 concepts to conform with the new editorial guidance on the naming convention for digits of hand and foot. 

1. • • Added 196 new descriptions.
     • Inactivated 174 descriptions.

Updates have been made to concepts for skin and/or subcutaneous tissue to conform to the editorial guidance on the naming convention for conjunction and disjunction. 

• • • • Added 84 new descriptions.
      • Inactivated 30 descriptions. 

2.2.2 Clinical finding

New concepts for clinical findings and disorders: 2005

Work completed on the following Content Projects:

• • • • IHTSDO-451 - Has definitional manifestation.

      • IHTSDO-
      772 - Suspected - findings / disorders, should be situations.
      • 592 and IHTSDO-
      412 - Intra-operative complication
      • 381 - Inactivate 91138005|Mental retardation (disorder)| and replace with 110359009|Intellectual disability (disorder)| with change to 281 descendant concepts.

Work commenced on the following Content Projects:

• • • • IHTSDO-703 - Inactivation of 'unilateral' concepts.
      • IHTSDO-614 - Rework hierarchy 441457006|Cyst (disorder)|.

Other content quality improvements:

• • • • For the January 2018 release the synonym of "occlusion" was inactivated from 26036001|Obstruction (morphologic abnormality) and added to 50173008|Complete obstruction (morphologic abnormality). 415582006|Stenosis (morphologic abnormality)| became a descendant of 25659002|Narrowed structure (morphologic abnormality). These changes resulted in a further 133 released concepts being reviewed and/or changed for the July 2018 release.

      • Added a new sufficiently defined concept of 763597000|Hereditary ataxia (disorder)| which resulting in changes to 40 concepts.

      • Hierarchy review/remodel descendants of 248595008|Sputum (finding)| with changes to 59 concepts.
      • Review/remodel "Progressive" disorders with changes to approximately 200 concepts.  A new clinical course qualifier value has been created: 255314001|Progressive (qualifier value)| as a subtype of 90734009|Chronic (qualifier value)|. Can be used to fully define progressive disorders using 246454002|Occurrence (attribute)| = progressive (qualifier value)
      • Review/remodel of "Acquired" disorders with changes to 697 concepts. A new period of life has been created: 767023003|Period of life beginning after birth and ending before death (qualifier value)|. This allows for a distinction to be made between acquired vs. congenital concepts and also permits existing ‘acquired’ concepts to be sufficiently defined. 
      • Remodel and fully define 63491006|Intermittent claudication (finding) and subtypes.
      • Review and remodel of 128200000|Complex regional pain syndrome (disorder)| and subtypes.
        
      • 7 new laboratory finding concepts added along with 30 changes made to existing laboratory concepts.
      • 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.
      • Remodel 3238004|Pericarditis (disorder)| and subtypes with primitive parent and changes to relationship groups where required to achieve consistency, approximately 100 concepts were remodeled.

2.2.3 Convergent Medical Terminologies (CMT)

New CMT concepts: 766

These were added across 3 domains:

• • • • CMT Neurology
      • CMT Musculoskeletal
      • CMT Radiology

2.2.4 Procedure Hierarchy

New concepts for procedure hierarchy: 911

Diagnostic Imaging - approximately 363 new concepts added including:

1. • • MRI 53
     • CT 38
     • Plain X-ray 15
     • Fluoroscopy 73
     • Imaging guided procedure (various modalities) 102
     • Ultrasonography 82

Work completed on the following Content Projects: 

• • • • IHTSDO-111 - Review of hierarchy 23968004|Colectomy (procedure) with inactivation of duplicate content, concepts remodeled with primitive parent and changes to relationship groups where required.
      • IHTSDO-691 - Remodel content 243185007 | Advanced life support (procedure) and subtypes.

Other content quality improvements:

1. • • Remodel and fully define 180081001|Correction of congenital deformity of hand (procedure)| and its descendants.

     • Fixed MRCM rule violation for 156 Evaluation procedures and removed Observable entities as values for Component Attribute.

     • Care program approach - realm specific concepts inactivated from International release.

2.2.5 Collaboration/Harmonization Projects

2.2.5.1 Orphanet

As a result of collaboration with Orphanet (http://www.orpha.net/consor/cgi-bin/index.php) 473 new SNOMED CT concepts have been created to represent rare diseases in the disorder hierarchy.

2.2.5.2 ICD-11 Harmonization plan

Added 1100 concepts equivalent to ICD-11 Mortality and Morbidity Statistics (ICD-11-MMS) codes; review and additions are ongoing based on updates to ICD-11-MMS.

2.2.5.3 LOINC

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

2.2.5.4 International Classification for Nursing Practice ( ICNP®)

74 new SNOMED CT concepts created as a requirement for the ICNP-SNOMED CT Equivalence Table.

2.2.5.5 Global Medical Device Nomenclature Agency (GMDNA)

64 new SNOMED CT concepts created in the Physical object hierarchy to support the GMDN collaboration agreement.

2.2.6 Morphologic Abnormality

New concepts added: 22

There are 5 updates for the ICD-O maps in 2018 July release.

2.2.7 Observable Entity

New concepts added: 52

Content quality improvements:

• • • • Inactivated 704318007 |Property type (attribute)| and replaced it with 370130000 |Property (attribute) for 162 modeled Observable entity concepts which had previously used 704318007 |Property type (attribute)|. Updated related MRCM rules and Editorial Guide.
        

2.2.8 Organism

New organism concepts added: 236

Changes to 29 existing concepts in the organism hierarchy.

2.2.9 Pharmaceutical / biologic product

Summary of changes

2.2.10 Veterinary Extension

2 concepts were moved to the Veterinary Extension. 

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. Do the file dates (20170131.txt,) need updating or do they remain the same? Sorry I don't know but just bringing it to your attention Andrew.

The SNOMED CT to ICD-10 Map is released as Refset 447562003 |ICD-10 complex map reference set (foundation metadata concept)|.

2.4.1.1 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.

2.4.1.2 Mapped content for July 2018

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

• • 2207 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 mapping@snomed.org

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 July 2018 International edition, the following Known Issues were identified, and agreed to be resolved in the next editing cycle (to be published in July 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 July 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 July 2018 International edition can be found here:

3.3 Technical updates

3.3.1  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.

3.3.2  Early visibility of impending change in the January 2019 International edition

Please see the following page for details of all upcoming changes planned for January 2019 and beyond:  Early Visibility - Planned changes to upcoming SNOMED International Release packages