News: CMS releases GEM mapping updates

CMS first released the new ICD-10-PCS codes and guidelines in May, followed by the new ICD-10-CM codes in June, and the ICD-10-CM guidelines in July. Last week, it released updates to the general equivalence mappings (GEMs) from CMS for both ICD-10-CM and ICD-10-PCS.

GEMs are a way to translate ICD-9 codes into ICD-10 codes and vice versa. In some cases, one ICD-9-CM code maps directly to one ICD-10-CM code. For example, paratyphoid fever A maps from ICD-9-CM code 002.1 directly to ICD-10-CM code A01.1.

More commonly, you’ll get a one-to-many match when you go from ICD-9-CM to ICD-10-CM. For example, in ICD-9-CM, simple chronic conjunctivitis goes from one code (372.11) to four codes:

• H10.421, simple chronic conjunctivitis, right eye
• H10.422, simple chronic conjunctivitis, left eye
• H10.423, simple chronic conjunctivitis, bilateral
• H10.429, simple chronic conjunctivitis, unspecified eye

You cannot code directly from the GEMs, but they will point you in the right direction. Look at your common diagnoses by ICD-9-CM code, then plug those codes into the GEMs and see where the GEMs take you. Use the GEMs to familiarize yourself with the ICD-10-CM codes (and the ICD-10-PCS codes for inpatient procedures) and see what the ICD-10-CM options are for commonly reported diagnoses. That can help you educate your physicians about any additional documentation they will need to provide for ICD-10.