Question: Pennsylvania Subscriber Answer: The difference: Medicare rules: 1. Your physician must have treated the patient's complication during a different session from the original procedure. 2. Your physician must have returned the patient to the operating room to treat the complication. If your physician took a Medicare patient to the operating room to deal with a complication during the global period of the original surgery, you'll have to append modifier 78 (Unplanned return to the operating/procedure room by the same physician following initial procedure for a related procedure during the postoperative period) to whatever services the physician reports for treating the complication. CPT rules: For E/M services to payers that follow CPT guidelines, you'll need to append modifier 24 (Unrelated evaluation and management service by the same physician during a postoperative period) to the CPT code to indicate that the service took place during the surgery's global period.