Overview

Representing language, dialect or specialty-specific term preferences is possible using a SNOMED CT extension. The logical design of SNOMED CT enables a single clinical idea to be associated with a range of terms or phrases from various languages, as depicted in the image below. In an extension, terms relevant for a particular country, speciality, hospital (or other organization) may be created, and different options for term preferences may be specified. Even within the same country, different regional dialects or specialty-specific languages exist may influence which synonyms are preferred. SNOMED CT supports this level of granularity for language preferences at the national or local level.

Examples of situations in which additional terms may be required together with the type of organisation that may be involved in producing these terms.

In section we explain the full set of steps for producing any extension. However, not all of these steps are required for all purposes. If producing an extension for the purpose of adding terms in languages and dialects, the following key steps are of particular relevance:

• Create descriptions

  • Principle and process for creating descriptions:

• Specify the acceptability of the created descriptions in a language reference set

is a multilingual clinical terminology that covers a broad scope of clinical concepts to an appropriate level of detail for international use. In addition, it provides an mechanism that allows to be customized to address terminology needs that are not met by the . This mechanism enables new concepts, relationships, descriptions and reference sets to be added to support national or local needs.

However, not every new terminology requirement requires a SNOMED CT extension to be created. Potential extension producers should be aware of situations in which it is beneficial to create an extension, and situations where alternatives may be preferable. The following table provides a summary.

When a SNOMED CT extension is required, the extension may serve a range of purposes. Successful extension producers must clearly understand the requirements and purpose of their extension, before deciding which types of SNOMED CT artifacts should be included.

Table below shows some typical purposes for a SNOMED CT extensions. For each purpose, the table includes some common use case examples and a list of SNOMED CT artifacts that should be included. For more information about each of these purposes, please click on the corresponding diagram.

Table: Purposes and use cases for extensions

The ability to tailor SNOMED CT to support specific use cases speaks to the adaptability of SNOMED CT, and any customization artifact that is beneficial to share may be useful to include in an extension. NRCs may need to configure SNOMED CT to match national requirements for reporting, analytics, language preferences etc.. Hence, following SNOMED CT reference sets may be included in an extension to meet a range of SNOMED CT use cases:

• A subset of SNOMED CT concepts or descriptions for use in a clinical speciality or practice

• Groups of concepts to support national reporting and analytics

• Prioritized components to support the logical display of search results

• Sets of components annotated with indicators that may trigger various guidelines or features

• Associations between SNOMED CT concepts, for example to represent language preferences or represent reasons for inactivation

In many cases, the terminology will be customized by referencing existing SNOMED CT components and linking these to additional information. The SNOMED CT reference set structure provides a standard representation for customized sets of SNOMED CT components. Different reference set types have been specified to meet particular needs and data structure requirements. All reference sets belong to a particular SNOMED CT Edition, and reference sets developed by Member countries or local organizations are included in their national or local extension.

Key Steps

In section we explain the full set of steps for producing any extension. However, not all of these steps are required for all purposes. If producing an extension for the purpose configuring SNOMED CT for a specific use case, the following key steps are of particular relevance:

• Create the reference set

  • Principle and process for creating a reference set in an extension:

  • See the for more information about the different reference set types and their usage

• Creating reference set members to represent each map record

Extensions can be used to add content to SNOMED CT. These additions can address perceived content gaps in SNOMED CT because content is:

• Outside of the defined scope of the International Edition, and has thus been intentionally excluded

• Within the scope of the International Edition, but is not included as it relates to a new clinical knowledge or a previously unreported omission

In some cases, a content gap will be addressed by adding content directly to the International Edition, but in other cases the content will be rejected for inclusion in the International Edition. When content is outside the scope of the International edition, yet required to support national or local needs, this content may be added to an extension . For example

• Content relevant to an entire country may be relevant to include in a national extension, for example

  • Concepts used for reporting and quality metrics in a specific country or region

  • Representation of specific procedural concepts such as a technique that is used nationally for testing purposes

  • Concepts that are mandated by government agencies that would otherwise be excluded from the International release by editorial policy

• Content relevant to a specific hospital may be included in a local extension, for example

  • Local interface terms or patient-friendly terms, added as extension descriptions which describe existing SNOMED CT concepts

  • Concepts representing specific hospital wards or beds

• Content relevant to a specific vendor may be included in a local extension, for example

  • System-specific interface terms or codes, added as extension descriptions which describe existing SNOMED CT concepts

As illustrated in the image below, content can be added to SNOMED CT by inclusion in the International Edition or in relevant extensions. National extensions will add the content relevant for multiple Affiliates (or stakeholders) within a country or member territory, whereas highly specific content, which is only relevant for a specific vendor product or hospital may be added in a local extension.

In some circumstances, extensions can be used to extend the expressivity of SNOMED CT, for example by expanding the concept model or by specifying additional terminology characteristics and features. SNOMED CT enables the following enhancements to expressivity to be made by adding terminology metadata.

• Creating a new reference set pattern, with new attributes

• Creating a new relationship type, i.e. a new attribute

• Creating a new description type

Once the required metadata has been added, the enhancement can be used within the extension and can be applied to SNOMED CT components in the extension, the International Edition, or any other modules on which the extension depends.

Extending the expressivity of SNOMED CT does not necessarily require the creation of new clinical content in SNOMED CT. However, it does require the addition of concepts within the hierarchy of SNOMED CT and in some cases the addition of reference set members to one of the metadata reference sets.

In section we explain the full set of steps for producing any extension. However, not all of these steps are required for all purposes. If producing an extension for the purpose adding content to SNOMED CT, the following key steps are of particular relevance:

• Create components

  • Principle and process for creating concepts:

  • Principle and process for creating descriptions:

  • If you need to specify defining characteristics for concepts, for example following the creation of a new concept. See section for information about the principles and process for creating relationships

Overview

When implementing SNOMED CT there is often a need to link SNOMED CT to other code systems. Examples of practical uses of a map are described in the table below:

In section we explain the full set of steps for producing any extension. However, not all of these steps are required for all purposes. If producing an extension for the purpose of representing a map between SNOMED CT and other code systems, the following key steps are of particular relevance:

• Create the map reference set

  • Principle and process for creating a reference set in an extension:

• Creating reference set members to represent each map record