Neurosurgery Coding Alert

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 the assistant surgeon assists with a portion of the operation.

Payment is not allowed for assistants at a surgery when it 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 a qualified resident isn’t available in a teaching facility, which means the assistant surgeon has to perform the entire procedure, then the physician must document the unavailability in the operative note, and you’ll append modifier 82 to the applicable CPT® code.

According to the Medicare Claims Processing Manual, the Centers for Medicare & Medicaid Services (CMS) lists several ways the qualified resident isn’t available, which include:

• 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 Modifier AS Use Circumstances

Medicare will pay for an assistant surgeon when an assistant is authorized for the procedure. However, when the provider performing the assistance is not a physician, a physician assistant (PA), nurse practitioner (NP), or a clinical nurse specialist (CNS) are qualified health care professionals that may report as an assistant at surgery. Keep in mind the physicians report as assistant surgeons using modifiers 80, 81 or 82, whereas a PA, NP, or CNS would report with a different modifier.

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.

Know if 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 if 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.