Modifier 53: Discontinued Procedure
Modifier 53 reports a procedure the physician started but had to stop. When it applies, how Medicare pays an incomplete colonoscopy, and 53 vs 52, 73 and 74.
Modifier 53 is a billing modifier for a surgical or diagnostic procedure that the physician started and then stopped because continuing would put the patient at risk or circumstances made it impossible to finish. It goes on the physician's claim; hospitals and ambulatory surgery centers report the same event with modifiers 73 or 74. Medicare pays a reduced amount, and for colonoscopy that amount is built into the fee schedule.
Key takeaways
- 53 means the procedure was started and could not be completed for the patient's safety or another unforeseen reason, decided by the physician.
- An elective cancellation before anesthesia or surgical prep is never 53.
- Incomplete colonoscopies (45378, 44388, G0105, G0121) with 53 have their own fee schedule values, based on half the inputs of the full code.
- For other codes, Noridian tells physicians to bill the share of the service completed: the claims system doesn't cut the payment for you.
- 53 doesn't go on E/M or anesthesia codes, or on facility claims.
Modifier 53 · payment effect
With and without the modifier
45378 without 53 · national office
$378.10
Colonoscopy
45378-53 · Contractor decides
Varies
Medicare contractors set the payment from documentation; there’s no fixed percentage.
When to use modifier 53
Use 53 on the professional claim when:
- The procedure was actually started: for surgery, after the patient was prepped or anesthesia began; for a diagnostic test, after it began.
- The physician chose to stop it because going on was unsafe for the patient or no longer possible, for example a sudden drop in blood pressure or an arrhythmia.
- The operative or procedure note says what was done, why it was stopped and how far it got.
Incomplete colonoscopy. When the scope can't be advanced to the cecum (or to the colon-small intestine anastomosis) because of unforeseen circumstances, bill 45378, G0105, G0121 or 44388 with 53. The fee schedule has specific values for those combinations, and since January 1, 2016 Medicare pays them from one-half the value of the inputs for the codes (Pub. 100-04, ch. 12, §30.1.B).
When not to use modifier 53
- The physician deliberately did less than the code describes from the start. That is modifier 52, reduced service.
- E/M visits and anesthesia codes. 53 doesn't apply to them.
- Hospital outpatient and ASC facility claims. Facilities use 73 (discontinued before anesthesia) or 74 (discontinued after anesthesia began).
- A completed procedure with a different result than hoped. If the service was fully performed, bill it without 53.
- A procedure finished by a less extensive code. If what was done fully meets another code's description, bill that code instead.
How modifier 53 affects payment
Outside colonoscopy, Medicare doesn't publish a percentage for 53. Noridian's guidance is to bill the share of the service that was completed (60% of the service performed means 60% of the allowed amount as your charge), because the claims system doesn't reduce the payment automatically. Expect the MAC to request the procedure note, and send it with the claim if your MAC asks for it.
For incomplete colonoscopies, payment comes from the specific 45378-53, 44388-53, G0105-53 and G0121-53 values in the fee schedule, so the reduction is already in the rate.
Modifier 53 vs 52, 73 and 74
| Modifier | Claim | Use it when | Payment |
|---|---|---|---|
| 53 | Physician | Procedure started and stopped for patient safety or circumstances | Reduced; colonoscopy has set values |
| 52 | Physician | Service intentionally reduced or partially performed by plan | Reduced; priced with documentation |
| 73 | Facility (OPPS, ASC) | Discontinued after prep, before anesthesia | Set by OPPS or ASC payment rules |
| 74 | Facility (OPPS, ASC) | Discontinued after anesthesia started or the procedure began | Set by OPPS or ASC payment rules |
The simplest test between 52 and 53: was the plan to do less (52), or did something force the physician to stop (53)?
FAQ
What is the difference between modifier 53 and 73?
53 is the physician's modifier for a procedure that was started and discontinued. 73 is the hospital outpatient or ASC facility's modifier for a procedure stopped after prep but before anesthesia. The same event can produce a 53 on the physician claim and a 73 or 74 on the facility claim.
What is a 52 and 53 modifier on a colonoscopy?
53 is for a colonoscopy the physician started but couldn't complete, such as when the scope couldn't reach the cecum. Medicare has specific fee schedule values for colonoscopy codes with 53. Modifier 52 is for a service intentionally reduced, which has different rules.
When do I use modifier 52 vs 53?
Use 52 when the physician decides in advance, or during the procedure by choice, to do less than the full service. Use 53 when the physician has to stop because of risk to the patient or circumstances outside their control.
Does modifier 53 reduce payment?
Yes. For colonoscopies the reduced values are built into the fee schedule. For other procedures the MAC prices the discontinued service; bill the share that was completed and keep the procedure note ready.
Can you bill modifier 53 if the procedure was canceled before anesthesia?
No. An elective cancellation before anesthesia induction or surgical preparation isn't billed with 53.
Keep reading
- Modifier 52 for intentionally reduced services.
- Modifier 22 for services that took substantially more work.
- Modifier 76 and modifier 77 for repeat procedures.
- Codes on this page: 45378 G0105 G0121 45385
Sources: CMS Medicare Claims Processing Manual, Pub. 100-04, ch. 12, §30.1.B (Transmittal 3368, CR 9317); Noridian JF Part B, Modifier 53 (updated May 9, 2025). Verified October 6, 2026.
