Question: Our anesthesia provider began administering MAC (monitored anesthesia care) and IV sedation to a patient having a Vertiflex procedure in an ASC. The patient became unresponsive and stopped breathing. Our provider assisted in ventilating the patient. After the patient awoke, the physician decided to cancel the procedure. Since anesthesia was provided and the procedure was canceled, would I still bill the service and include modifier 53? Wisconsin Subscriber Answer: You should only bill the total amount of anesthesia time and the associated anesthesia code. The surgeon will report the appropriate procedure code and will append modifier 53 (Discontinued procedure) to that. Remember, the anesthesia service was started and finished, including time spent ventilating the patient. Reduced payment will be applied due to the lesser amount of anesthesia time spent when the case was cancelled. The base surgical code is 22869 (Insertion of interlaminar/ interspinous process stabilization/distraction device, without open decompression or fusion, including image guidance when performed, lumbar; single level), which crosses to anesthesia code 00630 (Anesthesia for procedures in lumbar region; not otherwise specified). Include a diagnosis from the Z53 (Persons encountering health services for specific procedures and treatment, not carried out) code family (and supporting documentation) to help explain the situation. Diagnosis Z53.8 (Procedure and treatment not carried out for other reasons) might be your best option, depending on the surgeon’s opinion.