How would you code/bill an instance where the propofol anesthesia was administered by the anesthesiologist, and the patient had a reaction which made it necessary to stop the anesthesia and cancel the procedure. The colonoscope was not inserted yet, although a rectal exam was performed. I had found some documentation stating that I should bill the anesthesia only with the normal AA modifier and then the 53 modifier, attached to the anesthesia CPT code. Will this get paid without billing out a discontinued procedure CPT? I thought that I could bill out the anesthesia,with the modifier 53 and perhaps a low level office visit. Any help you can give would be appreciated.