Each quarter CMS makes updates to Medically Unlikely Edits (MUE’s) for all CPT’s. There are not always changes, but when there are, billing errors are prone to occur. The July 1, 2018 MUE list did not just include updates to allowable units for a few Pathology and Laboratory HCPCS (80000-89999), but also the MUE Adjudication Indicator (MAI) for some codes. The changes are as follows:
| HCPCS | Description | MUE | MAI | New MUE | New MAI |
| 81479 | Unlisted Molecular Path Code | 1 | Date of Service Edit:Clinical | 3 | Date of Service Edit: Clinical |
| 87481 | Candida Species, Amplified Probe Technique | 1 | 1 Line Edit | 2 | Date of Service Edit: Clinical |
| 88341 | IHC Stain, Each Additional Single Antibody | 9 | 1 Line Edit | 13 | Date of Service Edit: Clinical |
| 88344 | IHC Stain, Each Multiplex Antibody | 1 | 1 Line Edit | 6 | Date of Service Edit: Clinical |
| 88356 | Morphometric Analysis, Nerve | 1 | 1 Line Edit | 3 | Date of Service Edit: Clinical |
Particularly noteworthy is the change to the MUE for IHC stains (88341 and 88344) and the MAI associated with each. This changes claims submission and follow-up approaches in billing for these services. The MUE Adjudication Indicator indicates that additional units can no longer be split by line item and modified with no limit to total number billed. Instead, CMS is indicating that clinical standards are established for a given quantity of these stains and will expect documentation to support any amounts that exceed the established limit. The MUE for 88342 remains at 3, with an MAI of Date of Service Edit: Clinical.
APS maintains tables in its proprietary billing system specific to CMS’ MUE’s and modifies claims prior to submission in order to allow for clean claim submission and payment. Quarterly updates are in place to accommodate these changes. If you have questions about these changes, please contact your Practice Manager.
