Gastroenterology Coding Alert

As a coder specializing in general surgery, it’s crucial to understand the significance of modifiers in medical claims. Misuse or incorrect application of modifiers can lead to claim denials.

Specifically, if someone of another specialty serves as an assistant surgeon during a procedure, and that’s why it’s important to know the appropriate time and method to append certain modifiers.

Check out this guide to learn how to append assistant-at-surgery modifiers.

Understand When an Assistant Surgeon Is Necessary

According to Medicare guidelines, an assistant at surgery is “a physician who actively assists the physician in charge of a case in performing a surgical procedure.” A primary surgeon may require an assistant surgeon during a procedure for several reasons, including the complexity of the procedure or a patient having multiple comorbidities that could complicate the treatment. In those cases, the assistant surgeon works under the primary surgeon’s direct supervision.

The operative note should list the primary surgeon and the assistant surgeon. Plus, the documentation needs to include the assistant surgeon’s role during the procedure.

Your coding will depend on which surgeon you’re reporting on the claim. If you’re reporting the procedure for the primary surgeon, you’ll assign the correct procedure code without an assistant surgeon modifier. However, you’ll append an applicable modifier to the same procedure code when you’re billing for an assistant surgeon.

Master the Assistant Surgeon Modifiers

The CPT^® code set features three assistant-surgeon modifiers:

• 80 (Assistant surgeon)
• 81 (Minimum assistant surgeon)
• 82 (Assistant surgeon (when qualified resident surgeon not available))

Choosing between modifiers 80 and 81 comes down to the assistant surgeon’s involvement in the surgery. You’ll append modifier 80 if they participate in the entire procedure, but you’ll use modifier 81 when they assist with a portion of the operation.

Payment is not allowed for assistants at a surgery when the surgery is furnished in a teaching hospital that has a training program related to the medical specialty required for the surgical procedure and has a qualified resident available to perform the service. If the assistant surgeon has to perform the entire procedure, then you’ll append modifier 82 to the applicable CPT^® code. The Medicare Claims Processing Manual, by the Centers for Medicare & Medicaid Services (CMS) describes the following scenarios that would allow an assistant surgeon to help perform the surgery when the qualified resident isn’t available:

• A resident was working on other activities, rendering them unavailable.
• The resident doesn’t possess the necessary skills to assist with a complex surgery.
• The residency program has a limited number of residents.
• The patient requires urgent treatment due to a life-threatening condition, multiple traumatic injuries, or another emergency situation.

Analyze the Specific Circumstances for Modifier AS Use

Medicare will pay for an assistant surgeon when an assistant is authorized for the procedure. However, the provider performing the assistance must be a physician, physician assistant (PA), nurse practitioner (NP), or clinical nurse specialist (CNS).

In procedures where a PA, NP, or CNS assists during the surgery, you’ll append HCPCS Level II modifier AS (Physician assistant, nurse practitioner, or clinical nurse specialist services for assistant at surgery) to the surgery code.

When the healthcare professionals listed above act as surgery assistants, make sure you do not include modifier 80, too.

Why? According to the following Medicare Claims Processing Manual sections, only modifier AS will be reported on the claim:

• Section 110.2: “The AS modifier must be reported on the claim form when billing PA assistant-at-surgery services.”
• Section 120.1: “Only the AS modifier must be reported on the claim form when a NP or CNS bills assistant-at-surgery services.”

As always, you should review your individual payer preferences to check how they want billing for surgical assistants. Many commercial payers follow Medicare’s billing rules, but not all of them do. Some payers may want modifier AS, while others may not recognize it entirely.

Find out if the Procedure Allows Assistant Surgeon Billing

Billing for an assistant at surgery for Medicare reimbursement requires more than just appending the correct modifier. The Medicare Physician Fee Schedule (MPFS) features an assistant surgeon (Asst Surg) column that indicates whether a procedure allows an assistant. The indicator listed in the column will let you know the reimbursement rules for the procedure:

• 0: Medicare will allow payment for assistant at surgery only if there is documentation supporting medical necessity.
• 1: Medicare will not pay for assistant at surgery. Do not append modifier 80, 81, 82, or AS to these codes.
• 2: Medicare will allow payment for assistant at surgery. Append modifier 80, 81, 82, or AS to show that an assistant surgeon was involved in the encounter.
• 9: Assisted surgery concept doesn’t apply.

Payers won’t reimburse for assistants at surgery in every surgical case, even if you append 80, 81, 82, or AS to the claim. Medicare guidelines state that assistant at surgery services are eligible for reimbursement only when the procedure would require an assistant in 5 percent or more of claims submitted nationally. “A good guideline is that X, 0-, and 10-day global period procedures do not allow an assistant while 90-day procedures typically do. Always use the Medicare Physician Fee Schedule Database Lookup Tool to be sure,” says Terri Brame Joy, MBA, CPC, COC, CGSC, CPC-I, product manager, MRO, in Philadelphia.

Scenario: A surgeon performs a thoracotomy and captures three biopsies of the patient’s pleura. A pulmonologist acts as an assistant at the surgery.

For this scenario, you’ll assign 32098 (Thoracotomy, with biopsy(ies) of pleura) to report the procedure. Under the Asst Surg column of the MPFS, 32098 carries a “2,” which means Medicare will provide reimbursement for an assistant surgeon when you append the correct modifier to the code.

Mike Shaughnessy, BA, CPC, Development Editor, AAPC