Use Modifier 50 to Code Medicare Bilateral Surgery Claims

Are you billing Medicare correctly for bilateral surgical procedures? The Centers for Medicare & Medicaid Services (CMS) says many physicians are not.

Remember this rule for correct billing:

Report bilateral surgical procedure codes where the term "bilateral" is not in the descriptor using modifier 50 (indicating bilaterality) and one unit of service in a single line item. (See Code Carefully for Bilateral Procedures for more about bilateral procedure billing.

For example, when billing for a bilateral mastectomy, you would report the service to Medicare as a single line item with one unit of service: 19303 (Mastectomy, simple, complete) 50.

CMS has assigned CPT code 19303 a Medically Unlikely Edit (MUE) of 1; if you billed this code for more than one unit of service, the claim would deny as exceeding the MUE.

An MUE value is the maximum units of service that most physicians and providers would report for a HCPCS/CPT code for the vast majority of patients receiving the services for the same patient on the same date of service.

When billing Medicare, be sure to check if CMS has assigned an MUE value to the code(s) you are billing. Learn how to search for MUEs in the CMS publication, How to Use the Medicare National Correct Coding Initiative (NCCI) Tools (PDF). If you still have questions, contact TMA's Payment Advocacy staff at

Published July 22, 2014

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