NCHS and CMS have published General Equivalency Mappings (GEMs) as a translation reference between I-10 and I-9 diagnosis and procedure codes. These “one-to-one” mappings translate one I-10 code to either one I-9 code or one cluster of up to six ICD-9 codes. This is why the mappings are referred to as both one-to-one and one-to-many.
I-9 Code Clusters
In some cases it takes as many as six I-9 codes combined (clustered) to reproduce one I-10 code. According to CMS, “This is the case with I-9 principal procedure codes such as coronary angioplasty that require the use of ‘adjunct’ I-9 codes to provide additional detail.”
| I-10 Procedure | Corresponding I-9 Procedures |
| 02733ZZ: Dilation of Coronary Artery, Four or More Sites, Percutaneous Approach | 00.66: PTCA or coronary atherectomy |
| 00.43: Procedure on four or more vessels |
If the procedure was performed on four or more vessels, the “adjunct” 00.43 I-9 code must be applied in addition to 00.66 because some reimbursement systems may pay more for a procedure performed on four or more vessels.
I-9 Code Alternatives
According to CMS, “More than one I-9 code may be a valid translation of a given I-10 code. Which one of those I-9 codes is the most correct translation cannot be determined based on the meaning of the codes themselves.”
| I-10 Procedure | Corresponding I-9 Procedures |
| 0LQ70ZZ: Repair Right Hand Tendon, Open Approach | 83.61: Suture of tendon sheath |
| 83.64: Other suture of tendon |
ICD-10 Reimbursement Mapping*
Distribution of mappings to single I-9 codes and I-9 code clusters
| Code set | Mapped to single I-9 code |
Mapped to 2-code cluster | Mapped to 3-code cluster | Mapped to 4-code cluster | Mapped to 5-code cluster | Mapped to 6-code cluster | Total I-10 codes |
| ICD-10-CM (diagnosis) | 65,767 | 3,302 | 26 | 6 | 0 | 0 | 69,101 |
| ICD-10-PCS (procedure) | 69,657 | 1,211 | 583 | 458 | 36 | 12 | 71,957 |
For more information on the ICD-10 code impacts, complete the contact form located on the sidebar.