Question: I need advice on how to code for Medicare versus commercial payers when reporting 64405 as bilateral. I've seen several different ways that coders report it. What kinds of guidelines exist? Louisiana Subscriber Answer: When submitting 64405 (Injection, anesthetic agent; greater occipital nerve) as bilateral, Medicare requires that you include modifier 50 (Bilateral procedure) with a single unit of service and one line item. The correct way to report the service for commercial insurers will depend on the payer. Some want modifier 50, some want you to report separate lines of 64405 with modifiers LT (Left side) and RT (Right side), some want you to include modifier 51 (Multiple procedures) to distinguish bilaterality. Directions for billing bilateral services should be included in the payer's provider manual.