CPT modifier used for discontinued procedure. Under certain circumstances, the physician may elect to terminate a surgical or diagnostic procedure. Due to extenuating circumstances or those that threaten the well-being of the patient, it may be necessary to indicate that a surgical or diagnostic procedure was started but discontinued. This circumstance may be reported by adding the modifier -53 to the code for the discontinued procedure. This modifier is not used to report the elective cancellation of a procedure before the patient’s anesthesia induction and/or surgical preparation in the operating suite. For outpatient hospital/ambulatory surgery center (ACS), see modifier -73 and modifier -74 .