Follow the ICD-10-CM Road Map with GEM
This month we follow the ICD-10-CM roadmap to crosswalking with general equivalence mappings (GEMs). The GEM system, developed by the National Center for Health Statistics (NCHS), maps ICD-10-CM and the ICD-9-CM volumes one and two and helps facilities and payers create crosswalks. You can access it on the CMS Web site at: www.cms.hhs.gov/ICD10.
Mapping—or crosswalking—helps you find the corresponding diagnosis between two codes sets and their correlation. In ICD-9-CM, codes are three to five digits in length plus alphanumeric E and V codes, approximately 13,500 codes in total. ICD-10-CM consists of three to seven alphanumeric characters with more than 68,000 codes possible. There isn’t a simple crosswalk from ICD-9-CM to ICD-10-CM, and the GEM files attempt to organize the differences. When mapping a code from ICD-9-CM to ICD-10-CM, there may be more than one code in ICD-10-CM that maps to ICD-9-CM. There are separate GEM files for ICD-9-CM Volume 3 to ICD-10-PCS.
Follow the ICD-10-CM Road Map with GEM – Coding Edge July 2008