I have a patient who had an unrelated procedure done on the opposite hand within the original surgery 90 day global period. Would I use a 79 modifier on the 2nd surgery or a 78 modifier? It isn't a complication, it is just another procedure on the opposite hand. For example, Carpal tunnel done on left wrist and 2 months later it is done on the right wrist. I used LT/RT modifier but Medicare is denying it. Please help. Thank you!