Among different used healthcare terminology resources there is a need to link them to ease their interoperability. SNOMED CT is the most detailed clinical reference terminology for procedure used in the Electronic Health Record (EHR). WHO developed since 2006 an aggregated classification named ICHI required for statistics and resource allocation. It is based on an ontology framework defined in ISO 1828 named Categorial Structure (CAST) for surgical procedures. We present ICHI coding structure, ISO 1828 CAST standard for surgical procedures and SNOMED CT procedures hierarchy concept model and their relations. We demonstrate the obstacles to align ICHI coding structure with ISO 1828 CAST which can be linked with SNOMED CT procedures hierarchy concept model. We recommend to update ICHI coding structure to decrease the gap with ISO 1828 CAST and SNOMED CT concept model for procedures hierarchy to allow users to share the different terminology resources.
Keywords: Classification; Health care common procedure coding system; Knowledge; SNOMED CT.