Pathology/Lab Coding Alert

Question: I see that HCPCS 2020 deletes modifier GD. Does this impact coding for multiple units of a test that exceeds the MUE limit?

Codify Subscriber

Answer: Losing modifier GD (Units of service exceed medically unlikely edit [MUE] value and represent reasonable and necessary services) shouldn’t impact your coding when your lab legitimately exceeds the medically unlikely edits (MUEs) for a service.

Medicare provided guidance for how to override an MUE value, when appropriate, but never directed coders to use modifier GD, instead pointing to “distinct service” modifiers such as 59 (Distinct procedural service) or the following X{EPSU} modifiers:

• XE (Separate encounter…)
• XP (Separate practitioner…)
• XS (Separate structure…)
• XU (Unusual non-overlapping service…)

Alert: The MUE table includes a column for “MUE Adjudication Indicator” (MAI), which provides guidance about what circumstances allow you to override an MUE limit for a given code. If the code has an MAI of “1,” the code is adjudicated on a claim-line basis, meaning that you can’t exceed the number of MUE units on a claim line. You are allowed to use one of the distinct-service modifiers to override the edit, if circumstances warrant.

An MAI of “2” means that the frequency limit is absolute for a date of service — you cannot override the edit with a modifier.

An MAI of “3” means that the frequency limit is based on the date of service, and Medicare will automatically deny any claims in excess of that limit, even if you use an appropriate modifier. However, Medicare will consider an appeal with appropriate documentation.