Understanding the appropriate use of surgical modifiers is essential for accurate coding and compliance. Recent audits by the Office of Inspector General (OIG) have revealed significant billing inaccuracies related to co-surgeon and assistant-at-surgery procedures, underscoring the need for careful review and application of relevant guidelines.
OIG Findings on Modifier Usage
In a November 2022 report, the OIG reviewed 100 sampled services involving co-surgeon and assistant-at-surgery claims and identified a 69% error rate, including:
49% billed without the appropriate co-surgeon (modifier 62),
14% lacking the assistant-at-surgery modifier (modifiers 80, 81, 82, or AS),
6% classified as duplicate services.
Extrapolated across all applicable services, these findings estimate $4.9 million in improper Medicare payments from 2017 through 2019. To reduce errors and ensure compliance, coders must follow CMS guidelines and verify code-specific indicators in the Medicare Physician Fee Schedule Database (MPFSDB).
Assistant-at-Surgery Modifiers
Modifiers for assistant-at-surgery must be selected based on the provider type and the surgical context. Proper documentation must clearly identify the assistant and describe their role.
Modifier 80 – Applied when a physician assists during surgery.
Modifier 81 – Used when the assistance is minimal and provided by a physician.
Modifier 82 – Used in teaching hospitals when a qualified resident is unavailable, and a physician assists; documentation must justify the absence of a resident.
Modifier AS – Applied when a non-physician provider (PA, NP, CNS) assists.
MPFSDB ASST SURG Indicators:
0 – Payment restriction; supporting documentation required.
1 – Assistant-at-surgery not payable.
2 – Assistant-at-surgery payable.
9 – Concept does not apply.
Co-Surgeon Modifiers
When two surgeons perform distinct, reportable portions of a single procedure, both may bill the same CPT® code with modifier 62. Each surgeon must document their portion of the operative report.
MPFSDB CO SURG Indicators:
0 – Co-surgery not payable.
1 – Payable with medical necessity documentation.
2 – Co-surgeons permitted; documentation not required if two-specialty requirement is met.
9 – Concept does not apply.
Note: The Medicare Claims Processing Manual (Chapter 12, Section 40.8) is being revised to clarify that co-surgeon billing may apply to bilateral procedures and same-specialty providers, not just different specialties as previously stated.
The OIG has also recommended clearer guidance on the use of modifier 62 for spinal instrumentation procedures under Medicare Part B.
Team Surgery Modifiers
For complex procedures involving more than two surgeons with distinct expertise, use modifier 66. Each participating surgeon must submit a claim with supporting documentation establishing medical necessity, and the operative report must detail each provider’s contribution.
MPFSDB TEAM SURG Indicators:
0 – Team surgery not permitted.
1 – May be payable with documentation; reviewed on a by-report basis.
2 – Team surgery permitted; payable by report.
9 – Concept does not apply.
Important: Modifier 66 is only appropriate when all surgeons are collaborating on the same procedure. If they are performing separate procedures, modifier 66 does not apply. Additionally, multiple procedure rules apply to a surgeon who performs multiple procedures independently.
Validation and Compliance
To ensure claim accuracy and compliance with CMS policies:
Review the MPFSDB for appropriate modifier indicators.
Validate coding with National Correct Coding Initiative (NCCI) edits.
Perform internal audits of services involving multiple providers.
Proper use of modifiers and thorough documentation are critical to reducing audit risk, preventing claim denials, and maintaining billing integrity.