General Equivalence Mappings (GEMS)

The Centers for Medicare & Medicaid Services (CMS) and the Centers for Disease Control and Prevention (CDC) created the GEMs as a tool for the conversion of data from ICD-9-CM to ICD-10-CM and ICD-10-PCS and vice versa. The GEMs:

  • Assist with the conversion of ICD-9-CM codes to ICD-10-CM/PCS codes
  • Assist with the conversion of ICD-10-CM/PCS codes back to ICD-9-CM
  • Ensure that consistency in national data is maintained

CMS and CDC made a commitment to update the GEMs annually along with the updates to ICD-10-CM/PCS during the transition period prior to ICD-10 implementation. The GEMs will only be maintained for 3 years beyond the October 1, 2015, ICD-10-CM/PCS implementation date for all HIPAA-covered entities. The GEMs are not a substitute for learning how to use ICD-10-CM and ICD-10-PCS. Providers’ coding staff will assign codes describing patients’ encounters from the ICD-10-CM and ICD-10-PCS code books or encoder systems. The GEMs are not used to code patient encounters.

For additional information, please visit: