Modifier 73 indicates a facility-level outpatient hospital or ASC procedure that was discontinued after the patient was prepared and taken to the procedure/operating room but before any anesthesia was administered. It is facility-only (physicians use modifier 53 on professional claims) and applies when termination is due to extenuating circumstances or threats to patient well‑being (for example unstable vitals or equipment failure). Documentation must confirm the patient was prepped and physically in the procedure room, state the clinical reason for termination, and explicitly note that no anesthesia or sedation was given.

When billed under Medicare OPPS/ASC rules, services reported with modifier 73 are paid at approximately 50% of the full procedural facility payment to reflect resources expended despite the procedure not proceeding; for device‑intensive procedures CMS removes the device allowance before the 50% reduction. Commercial payers commonly follow a similar approach (for example, Regence reimburses at 50% of the allowable amount) and many payers expect only the primary intended procedure to be billed with modifier 73. Modifier 73 must not be used if anesthesia was administered (modifier 74 is appropriate in that situation), and it is not used on physician professional claims (modifier 53 is used by the operating provider when applicable).