Comparison of existing classifications for coding congenital malformation and genetic syndromes.

One thousand consecutive new registrations at the B.C. Health Surveillance Registry were coded by means of ICD (8th Edition), Cardiff Classification, and SNOMED systems. The Cardiff system uses the basic ICD number with important fifth and sixth digit modifiers, which improve discrimination. In certain conditions, however, the basic three-digit number differs from that in ICD and hence comparability is not always possible. The SNOMED system has six subcategories, followed by a five-digit code. These subcategories deal with Function, Disease, Topography, Etiology, Morphology, and Procedure. For our particular needs, the SNOMED system was not entirely satisfactory as it has not expanded sufficiently for many of the malformation syndromes. For hospital use, though, the SNOMED system may have numerous advantages over other existing systems.