Snomed-CT is a structured terminology that is widely used in healthcare. Created by the College of American Pathologists, it is now maintained by the International Healthcare Terminology Standards Development Organization. CDA clinical codes are often taken from Snomed-CT, and in some countries this is a required use.

HL7Connect includes a Snomed Logic reasoning engine that is able to test whether one Snomed Term is subsumed by another. At present, the engine is only able to work with pre-coordinated terms. This engine can be used when routing CDA documents (i.e. cc: any bacterial infection to the infection control unit). In addition, the snomed engine is available in the scripts API (Kernel.SnomedIsA(childTerm, parentTerm) in VBScript/Javascript or just SnomedIsA(childTerm, parentTerm) in KScript). You can also view the Snomed-CT definitions in the system through the knowledge base.

Because of the way that Snomed-CT licensing works, HL7Connect does not include it's own copy of the definitions. If you wish to use the Snomed reasoner, you will need to Import a set of Snomed Definitions.

Importing the Snomed definitions

  1. You need a copy of the files sct_concepts_[X].txt, sct_description[X].txt, and sct_relationships_[X].txt. These files are part of the standard Snomed-CT distribution. [X] is usually a date and must be the same for all the files, and they must be in the same folder.
  2. You can modify the files before importing, to add new definitions or subset the definitions, but referential integrity between the files must be maintained. Note that there is no real performance reason to subset the definitions; the in memory structure is both fast and dense.
  3. Run the Manager
  4. Choose the Utilities Tab
  5. Click on the Import Snomed button
  6. Choose the concepts file from step #1
  7. Once the import is complete (takes some time), you need to restart HL7Connect

Note that the import requires about 1GB of memory, and a loaded snomed set uses 100MB extra RAM. These numbers are variable - they depend on the specifics of the snomed data loaded. The amount of work remaining during an import is a best guess based on the last imported data set.

© Kestral Computing P/L 2000-2015. HL7Connect v2.00-063 generated on 30-Nov 2015
Keywords: Snomed-CT