Modifier Coding Alert

Multiply the MPFS calculation results by up to 85 percent.

Coding a procedure can be challenging enough, but throw in an assistant surgeon and the challenges multiply. With three assistant surgeon modifiers to choose from, you need to ensure that the one you select best represents the clinical scenario you’re reporting.

Choose the wrong modifier and your surgeons might not get the payment they deserve. Read on to learn the tricks of correctly applying assistant surgeon modifiers.

Get to Know the 3 Assistant Surgeon Modifiers

Your provider may use an assistant surgeon for several reasons, such as when the procedure or the patient’s condition is complex. The assistant surgeon works under the direct supervision of the principal surgeon and is often in the same specialty as the principal surgeon. When an assistant participates in a procedure, you have three modifiers to choose from to correctly report to case. 

When an assistant surgeon assists an operating or principal surgeon during an entire procedure, the code requires modifier 80 (Assistant surgeon).

When your provider needs surgical assistance for only part of a procedure, you’ll use modifier 81(Minimum assistant surgeon).

When a physician or other qualified provider, such as a physician assistant, assists for the entire surgical procedure because a medical resident was unavailable to assist, attach modifier 82(Assistant surgeon [when qualified resident surgeon not available]).

“Modifier 82 is used in teaching hospitals where a resident could be used[but wasn’t available] as an assistant surgeon,” says Robin E. Richards, CPC, a senior coder in Pittsburgh, Pa. “Modifier 82 indicates that a physician was required as an assistant because the surgery was difficult or the residents were not experienced enough with that procedure.”

Use Modifier AS For Non-Physician Assistants 

Medicare pays for a surgical assistant when the procedure is authorized for an assistant and the person performing the service is a physician, physician assistant (PA), nurse practitioner (NP), or a clinical nurse specialist (CNS). 

When a PA, NP, or a CNS assists at surgery, attach modifier AS (Physician assistant, nurse practitioner, or clinical nurse specialist services for assistant at surgery) to the surgical code along with modifier 80, 81, or 82. 

“Modifier AS is used when a certified PA performs a procedure,” Richards explains. “If they are the assistant surgeon, it should be used in addition to the 80 or 82.”

Without AS, modifiers 80, 81, and 82 indicate that a physician was the surgical assistant. Claims you submit that include modifier AS without modifier 80, 81, or 82 will be returned to you.

Example: Your surgeon performs an open repair on a patient’s sternum, and you report 21825 (Open treatment of sternum fracture with or without skeletal fixation) for the repair. A PA in your practice assists with the surgery. You should attach modifiers 80 and AS to 21825 for the PA’s work.

Beware: Not all payers follow Medicare’s rules. Be sure to query each of your payers to find out their policies on billing for surgical assistants. They may want only the modifier AS or they may not recognize it at all.

Understand the Payment Impact

To calculate the payment you can expect to receive if your physician assists at surgery, you will take the facility-specific Medicare Physician Fee Schedule (MPFS) amount and multiply it by a 16 percent assistant at surgery reduction amount. Take that amount and then multiply by 80 percent.

Calculation:(MPFS feex0.16) x 80 percent

To determine the payment amount for your PA, NP, or CNS assisting at surgery, take the facility-specific MPFS amount and multiply it by a 16 percent assistant-at-surgery reduction amount. Take that amount and multiply it by an 85 percent non-physician practitioner reduction and then multiple that by 80 percent.

Calculation:(MPFS fee x 0.16 x0.85) x 80 percent

Watch for: When services are performed at a critical access hospital (CAH), the formula is multiplied by 115 percent.

Consult the MPFS

Before billing for an assistant at surgery using modifiers 80, 81, 82, or AS, be sure to check the ASST SURG column of the MPFS to be sure that the procedure(s) allows an assistant.

Payers will not reimburse you for assistants at surgery in all cases, regardless of the modifier(s) you attach to the claim. For Medicare, assistant at surgery services are eligible for reimbursement only when national claims data indicates the procedure would require an assistant in at least 5 percent of the claims based on a national average, according to Medicare guidelines.

If you find a 0 in column T, Medicare will allow payment (upon satisfactory review) for an assistant at surgery if you submit supporting documentation to establish medical necessity.

Example: Providers would need to submit medical necessity for a surgical assistant for 15650 (Transfer, intermediate, of any pedicle flap [e.g., abdomen to wrist, walking tube], any location).

A 1 in the ASST SURG column tells you that an assistant at surgery will never be paid. You would never apply modifier 80, 81, 82, or AS to these codes.

Medicare will pay routinely only for procedures with a 2 in the ASST SURG column of the fee schedule database. You should attach modifier 80, 81, 82, or AS to these codes to indicate that there was an assistant at surgery.

Example: Code 43620 (Gastrectomy, total; with esophagoenterostomy) has a 2 indicator in the ASST SURG column.

A 9 in the ASST SURG column indicates that the assisted surgery concept does not apply. You would never attach modifier 80, 81, 82, or AS to these codes. Many of the N status or non-covered codes carry a 9 in the assistant at surgery column (for example 65771, Radial keratotomy).