CPR’s “Coding Corner” focuses on coding, compliance, and documentation issues relating specifically to physician billing. This month’s tip comes from Deborah Marsh, senior content specialist for AAPC, a training and credentialing association for the business side of health care.

Medicare and other payors may provide extra payment when a procedure requires an assistant surgeon. But any time additional payment is involved, you’ve got to be sure you understand the rules and comply with them because you know payors will be checking your claims. Below we’ll focus in particular on physician assistants (PA) as assistant surgeons, but many of these medical coding rules apply to any assistant surgeon.

1. Know which assistant surgeon modifier to append
When a PA serves as an assistant at surgery, the correct modifier to report to Medicare is AS Physician assistant, nurse practitioner, or clinical nurse specialist services for assistant at surgery. You can confirm with other payors whether they accept this HCPCS Level II modifier.

Because modifier AS specifically lists a PA as one of the providers the modifier applies to, this option is more specific than these modifiers from the CPT^® code set:

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

2. Check whether the code allows assistant payment
Before you report the services of an assistant surgeon, check the Medicare Physician Fee Schedule (PFS) to determine whether Medicare allows assistant surgeon payment for your code (or check with your specific payor if it does not apply Medicare rules).

The relevant payment policy indicator is titled “assistant at surgery” or abbreviated to “ASST SURG” in the PFS Relative Value Files. Below you’ll find the indicator definitions and an example code for each:

• “0,” “Payment restriction for assistants at surgery applies to this procedure unless supporting documentation is submitted to establish medical necessity.”
  
  Example: 15836 Excision, excessive skin and subcutaneous tissue (includes lipectomy); arm
   
• “1,” “Statutory payment restriction for assistants at surgery applies to this procedure. Assistant at surgery may not be paid.”
  
  Example: 63650 Percutaneous implantation of neurostimulator electrode array, epidural
   
• “2, “Payment restriction for assistants at surgery does not apply to this procedure. Assistant at surgery may be paid.”
  
  Example: 63685 Insertion or replacement of spinal neurostimulator pulse generator or receiver, direct or inductive coupling
   
• “9,” “Concept does not apply.”
  
  Example: 99601 Home infusion/specialty drug administration, per visit (up to 2 hours).

3. Be sure assistant work qualifies as separately reportable
Even if the code allows assistant surgeon payment, you need to be sure the work performed was substantial enough to support separate reporting. Finding guidance on specific services that qualify can be difficult, but an example you may find helpful is the EmblemHealth “Assistant Surgeon Reimbursement Policy.”

For instance, the EmblemHealth policy states, “The primary surgeon may elect to have some services performed by an assistant surgeon that are included in the primary surgeon’s reimbursement for the procedure performed. In this case, the assistant surgeon’s services are not eligible for separate reimbursement. Here are examples of these type services: 1. Routine opening and/or closing of the surgical site 2. Performing post-operative monitoring.”

When you do separately report the services of an assistant surgeon, make sure the operative note specifies what the assistant surgeon did and, if possible, why the procedure required an assistant. Thorough documentation will help support payment for the assistant surgeon if the payor requests the medical record.