I'm having trouble wrapping my head around when or if to use mod.52 in an ASC setting. CMS ASC billing guidelines as provided by NHIC, our Medicare FI, only refer to mod. 52 in conjunction with radiology procedures not requiring anesthesia. The use of mod. 74 as described in the billing guidelines seems to indicate that it's used for medical complications arising after inducement of anesthesia. What if the surgeon is reducing the service simply because the full procedure is not necessary? Help, please.