HCPCS Modifier AD

Published 07/16/2020

HCPCS Modifier AD — medical supervision by a physician: more than four concurrent anesthesia procedures.

Guidelines and Instructions
  • This modifier may only be submitted with anesthesia procedure codes (e.g., CPT codes 00100 through 01999). Payment for services that are medically supervised is based on three base units per procedure with an additional unit of time if the physician documents that he or she was present at induction.
  • The units field must always be "1" when this modifier is submitted
Physician services may be reimbursed at the medically supervised rate in the following situations:
  • The anesthesiologist is involved in furnishing more than four procedures concurrently
  • The anesthesiologist is performing other services while directing the concurrent procedures. There are several exceptions to this requirement:
    • Addressing an emergency of short duration in the immediate area
    • Administering an epidural or caudal anesthetic to ease labor pain
    • Periodic (rather than continuous) monitoring of an obstetrical patient
    • Receiving patients entering the operating suite for the next surgery
    • Checking or discharging patients in the recovery room
    • Handling scheduling matters
  • These exceptions do not apply if the physician:
    • Leaves the operating suite for other than short durations
    • Devotes extensive time to an emergency case
    • Is otherwise not available to respond to the immediate needs of surgical patient


  • CMS Pub. 100-04, Chapter 12 (PDF, 1.10 MB)
    • Definitions of personally performed, medically directed and medically supervised: Section 50
    • Definition of concurrent procedures: Section 50J
    • Anesthesia modifiers: Section 50K

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