Modifier 73 is used by Hospital Outpatient Departments (HOPDs) and Ambulatory Surgical Centers (ASCs) to report a planned surgical or diagnostic procedure that is discontinued before anesthesia is administered because of extenuating circumstances or circumstances that threaten the patient’s well-being.

Unlike Modifier 53, which is generally used by physicians to report discontinued procedures, Modifier 73 is a facility modifier used only by outpatient hospitals and ASCs. It allows facilities to receive partial reimbursement for the resources used in preparing the patient and procedure room even though the procedure was not completed. CMS specifically limits the use of Modifier 73 to facilities and only when anesthesia was planned but had not yet been administered.

Modifier Number

Modifier Name

Discontinued Outpatient Hospital/Ambulatory Surgery Center (ASC) Procedure Prior to the Administration of Anesthesia

Plain English Explanation

Modifier 73 tells the payer:

“The patient was fully prepared and taken to the procedure room, but the procedure had to be cancelled before anesthesia was administered because continuing would have jeopardized the patient’s health or due to other extenuating circumstances.”

Purpose of Modifier 73

Modifier 73 is used to:

Report discontinued outpatient surgical or diagnostic procedures.
Recognize facility resources already consumed.
Support partial reimbursement under Medicare OPPS/ASC payment rules.
Distinguish procedures discontinued before anesthesia from those discontinued after anesthesia.

Understanding Modifier 73

CMS allows Modifier 73 only when all of the following conditions are met:

The procedure was scheduled.
The patient was prepared for surgery.
The patient was taken into the operating/procedure room.
Anesthesia was planned.
No anesthesia had yet been administered.
The procedure was cancelled because of extenuating circumstances or concerns for patient safety.

Preparation alone is not enough. The patient must already be in the room where the procedure would have been performed.

When to Use Modifier 73

Modifier 73 is appropriate when:

The patient develops unstable blood pressure before anesthesia.
Cardiac arrhythmia is detected immediately before anesthesia.
Oxygen saturation becomes dangerously low.
Equipment failure makes proceeding unsafe.
The physician determines cancellation is necessary for patient safety.
The patient has already entered the procedure room.

Common Examples

✔ Colonoscopy cancelled before sedation because the patient develops chest pain.

✔ Cataract surgery cancelled after patient preparation but before local anesthesia due to uncontrolled hypertension.

✔ Orthopedic procedure cancelled because newly identified cardiac instability places the patient at risk.

✔ Endoscopic procedure stopped before anesthesia because of equipment malfunction.

When NOT to Use Modifier 73

Do not use Modifier 73 when:

The procedure is cancelled before the patient enters the procedure room.
The cancellation is elective.
No anesthesia was planned.
Anesthesia has already been administered (Modifier 74 may apply).
Billing physician professional services (Modifier 53 may be appropriate instead).

CMS specifically states that physicians should not report Modifier 73 on professional claims.

Medicare Rules

Important Medicare rules include:

Applies only to HOPDs and ASCs.
Patient must be prepared and taken to the procedure room.
Procedure must require planned anesthesia.
No anesthesia may have been administered.
Cancellation must result from extenuating circumstances or threats to patient well-being.
Elective cancellations are not billable with Modifier 73.

Under OPPS, Medicare generally pays 50% of the normal facility payment for eligible discontinued procedures reported with Modifier 73, subject to applicable payment adjustments.

Commercial Insurance Rules

Commercial payer policies vary.

Many insurers:

Follow CMS guidance.
Restrict Modifier 73 to facility claims.
Require documentation explaining why the procedure was discontinued.
Require operative or nursing notes.
May have different reimbursement methodologies.

Always review payer-specific billing policies.

Documentation Requirements

Documentation should include:

Planned procedure.
Date of service.
Reason for discontinuation.
Confirmation that the patient entered the procedure room.
Confirmation that anesthesia had not been administered.
Physician order to discontinue.
Nursing documentation.
Operative or procedural notes.

Real Billing Examples

Example 1 – Colonoscopy

A patient is brought into the endoscopy suite for a planned colonoscopy. Before moderate sedation begins, the patient develops acute chest pain and severe hypertension.

The physician cancels the procedure.

Modifier 73 is appropriate.

Example 2 – Cataract Surgery

The patient is prepped and positioned in the operating room. Before local anesthesia is administered, the patient develops a dangerous cardiac arrhythmia.

The surgery is discontinued.

Modifier 73 is appropriate.

Example 3 – Incorrect Use

A patient calls the ASC the morning of surgery to cancel because of a family emergency.

Modifier 73 should NOT be reported.

CMS-1500 / UB-04 Billing Example

Field	Example
Procedure Code	Planned surgical CPT®/HCPCS code
Modifier	73
Diagnosis Pointer	Appropriate ICD-10-CM diagnosis
Units	1
Bill Type	Outpatient Hospital/ASC

Note: Modifier 73 is generally reported on facility claims (UB-04) rather than physician professional claims.

Common Denial Reasons

Patient never entered the procedure room.
Anesthesia had already begun.
Elective cancellation.
Procedure did not require anesthesia.
Modifier billed on physician claim.
Insufficient documentation.

How to Correct the Denial

Review the Explanation of Benefits (EOB) or Electronic Remittance Advice (ERA).
Confirm the patient entered the procedure room.
Verify anesthesia had not been administered.
Submit operative, nursing, and physician documentation.
Demonstrate the cancellation resulted from extenuating circumstances.
Appeal with supporting records when appropriate.

Coding Tips

Modifier 73 is a facility modifier, not a physician modifier.
Verify that anesthesia was planned but not administered.
Ensure the patient had already entered the procedure room.
Do not use Modifier 73 for elective cancellations.
Review payer-specific outpatient billing policies.

Modifier 73 vs Modifier 74 vs Modifier 53

Modifier	Purpose
73	Facility procedure discontinued before anesthesia.
74	Facility procedure discontinued after anesthesia or after the procedure has begun.
53	Physician discontinued procedure due to patient safety or extenuating circumstances.

Modifier 73 vs Modifier 52

Modifier	Purpose
73	Procedure discontinued before anesthesia because of extenuating circumstances.
52	Reduced services; the procedure was intentionally reduced or partially completed, not necessarily because of patient safety.

Frequently Asked Questions (FAQs)

Q1. What is Modifier 73?

Answer: Modifier 73 reports an outpatient hospital or ASC procedure that is discontinued before anesthesia is administered because of extenuating circumstances or concerns for patient safety.

Q2. Who reports Modifier 73?

Answer: Modifier 73 is reported by hospital outpatient departments and ambulatory surgery centers, not by physicians.

Q3. Does the patient have to enter the procedure room?

Answer: Yes. CMS requires that the patient be prepared and taken to the room where the procedure would have been performed before Modifier 73 may be used.

Q4. How is Modifier 73 reimbursed by Medicare?

Answer: Eligible procedures are generally paid at 50% of the normal OPPS facility payment, subject to Medicare payment rules and adjustments.

AR Caller Tips

When following up on a denied Modifier 73 claim:

Confirm the claim was submitted by the facility.
Verify anesthesia had not been administered.
Confirm the patient entered the procedure room.
Request review of operative and nursing documentation.
Record the payer representative’s name, reference number, and next steps.

Interview Questions

Question 1

What is Modifier 73?

Answer: A facility modifier used to report outpatient or ASC procedures discontinued before anesthesia because of extenuating circumstances.

Question 2

What is the difference between Modifier 73 and Modifier 74?

Answer: Modifier 73 is used before anesthesia, whereas Modifier 74 is used after anesthesia has been administered or the procedure has begun.

Question 3

Can physicians bill Modifier 73?

Answer: No. Modifier 73 is intended for facility billing by HOPDs and ASCs.

Practice Scenario

Scenario

A patient arrives at an ambulatory surgery center for a planned laparoscopic procedure. The patient is prepared, moved into the operating room, and connected to monitoring equipment. Before local or general anesthesia is administered, the patient develops severe hypotension and ventricular tachycardia. The surgeon determines it is unsafe to proceed and cancels the procedure.

Question

Should Modifier 73 be reported?

Answer

Yes. Because the patient had entered the procedure room, anesthesia had not yet been administered, and the procedure was discontinued due to circumstances threatening the patient’s well-being, Modifier 73 is appropriate for the facility claim.

Related Modifiers

Modifier 53 – Discontinued Procedure
Modifier 52 – Reduced Services
Modifier 74 – Discontinued Procedure After Administration of Anesthesia
Modifier 22 – Increased Procedural Services

Common Billing Mistakes

Using Modifier 73 on physician claims.
Reporting Modifier 73 after anesthesia has been administered.
Reporting elective cancellations.
Using Modifier 73 when the patient never entered the procedure room.
Failing to document the reason for discontinuation.

Key Takeaways

Modifier 73 is a facility-only modifier.
It applies to HOPDs and ASCs.
The patient must be prepared and in the procedure room.
No anesthesia may have been administered.
The cancellation must be due to extenuating circumstances or patient safety concerns.
Medicare generally reimburses eligible Modifier 73 procedures at 50% of the normal facility payment.

References

CMS Medicare Claims Processing Manual, Chapter 4, Section 20.6.4 – Modifiers 73 and 74.
CMS Recovery Audit Program – Modifier 73 and 74 Documentation Requirements.
First Coast Service Options – Modifier 73 Fact Sheet (2026).
AMA CPT® Professional Edition (licensed codebook).

Conclusion

Modifier 73 is a specialized facility modifier that recognizes the resources consumed when an outpatient hospital or ASC procedure must be discontinued before anesthesia is administered because of extenuating circumstances or patient safety concerns. Proper use requires verifying that the patient entered the procedure room, no anesthesia was administered, and the cancellation was medically necessary. Accurate documentation and adherence to CMS guidelines help reduce denials and support compliant reimbursement.

Educational Disclaimer

This article was prepared with the assistance of artificial intelligence (AI) for educational and informational purposes. It is based on publicly available CMS guidance, Medicare billing resources, and general medical billing principles. It is not an official publication of the American Medical Association (AMA), CMS, or any insurance payer. CPT® is a registered trademark of the American Medical Association. Always consult the latest AMA CPT® codebook, CMS manuals, Medicare Administrative Contractor (MAC) guidance, National Correct Coding Initiative (NCCI) policies, and payer-specific billing policies before coding, billing, or submitting claims.