Ask Dr. Z

There has been confusion surrounding the 2020 MUE revision from one to two for add-on code 93657. A prior reference in CPT Assistant (July 2013, pages 7-9) states that 93657 can only be reported once per operative session. If there are two additional afib ablations performed (i.e., anterior roof and posterior wall), is it possible to bill two units of 93657 if they are performed in the same surgical session and by the same provider? If so, which modifier should be used on the second 93657? Or, should we bill one per operative session, only billing two if the patient has to return to the operating room for a repeat ablation with pulmonary vein isolation and an additional afib ablation on the same date of service but a separate surgical session?