Author: Jessica Sullivan, CPC
Remote Coder – Pinnacle Integrated Coding Solutions

(303) 801-0111

When reviewing surgeries in order to determine whether an assistant is billable, coders and their providers should always be aware of what is needed in terms of necessity and documentation. Here are the three main factors that need to be addressed for assistant surgeons:


Is additional reimbursement allowed for a surgical assistant for that particular procedure?


Has the assistant’s role in the surgery been properly documented?


Are you applying the appropriate modifier?


After taking the elements listed above into account, there is always the chance that the payer will not reimburse the assistant’s efforts. Surgical assistance must be deemed medically necessary (per the payer’s standards) to warrant additional payment. The surgeon should specify in the body of the operative report what procedure or portions of a procedure the assistant performed. It is inadequate to just list the assistant’s name. The surgeon must clearly explain in the “indications” paragraph of the note why an assistant was necessary, and that he or she was involved in the actual performance of the covered surgical procedure, and not simply there to perform other ancillary services.


CMS has developed an assistant surgeon reimbursement policy. The following link leads you to all the PFS files.


Medicare specifies the procedures for which it allows additional payment for a surgical assistant, as identified by the “ASST SURG” column of the Medicare Physician Fee Schedule (“MPFS”) Relative Value File. If Medicare does not allow payment for an assistant at surgery, you cannot charge the patient, even if using an advanced beneficiary notice (“ABN”).


Assist-at-surgery indicators are outlined here:


2:  Assistant at surgery may be paid.


0:  Additional documentation is needed to substantiate medical necessity.


1:  Assistant surgeon will not be paid.


9:  Assistant surgeon concept does not apply.


Below are a few examples of surgeries with their corresponding indicator:


CPT® Short Descriptor ASST SURG Indicator
20985 Computer-assisted surgical navigation 0
63664 Revision of spinal neurostimulator 2
20610 Arthrocentesis, major joint or bursa 1
15850 Removal of sutures 9

Now that you’ve decided if the payor will allow for reimbursement and that medical necessity is documented, it is time to turn your attention to proper reporting. As always, make sure you are following your region’s MAC, as well as any third-party payors to determine which modifier to append.


Modifier 80 Assistant surgeon: Modifier 80 identifies services provided by a surgical assistant who is a medical doctor. Append this modifier only to the primary surgical service.


For example, an assistant surgeon frequently is used during arthrodesis surgery. The assistant helps to hold the vertebrae in place and assist in harvesting and placing the bone graft. In such a case, the primary surgeon might report 22610 Arthrodesis, posterior or posterolateral technique, single level; thoracic (with or without transverse technique), while the assistant surgeon would report 22610-80.


Modifier 82 Assistant surgeon (when qualified resident surgeon not available): Append modifier 82 only in a teaching hospital setting and only if a qualified resident is not available to assist during surgery.


For example, a lung hernia through the chest wall needs immediate repair in a teaching hospital setting. The residents on call are assisting in another procedure, and a second thoracic surgeon assists the primary surgeon. In this case, the primary surgeon reports 32800 Repair lung hernia through chest wall, while the assistant surgeon reports 32800-82.


The assistant surgeon should document clearly in the operative report why a resident was not involved in the case. You may also use Box 19 on the CMS-1500 form to indicate why a qualified resident was not able to assist during the surgery.


Modifier AS Physician assistant, nurse practitioner, or clinical nurse specialist services for assistant at surgery: Use this modifier for Medicare if a physician assistant (“PA”), nurse practitioner (“NP”), or clinical nurse specialist—rather than a medical doctor or doctor of osteopathic medicine—assists during a surgical procedure.


According to CMS MLN #MM6123:  Be aware that when you use Modifier AS, you must also use Modifier 80, 81, or 82 because using these modifiers without modifier AS indicates that a physician served as the surgical assistant. Claims that you submit with modifier AS and without modifier 80, 81 or 82 will be returned to you.


Modifier 81 Minimum assistant at surgery: Modifier 81 describes minimal assistance during surgery by another physician. Payers may also allow modifier 81 to report a second physician in the operating room for a small, selective portion of a particular procedure (such as opening and closure only).