Neurosurgery Coding Alert

If your payer doesn't use software that sorts procedures according to their assigned relative value units (RVUs), you must be cautious when appling modifier -51 (Multiple procedures), or risk losing reimbursement.

If you append modifier -51 to the primary (highest-valued) procedure, the insurer will fully reimburse a lower-paying code while reducing payment for the primary procedure, thereby lowering overall reimbursement.

Expect reductions: Payers don't pay multiple-procedure claims at 100 percent, explains Alice Church, CCS-P, coding and reimbursement analyst for Wolcott, Wood & Taylor Inc. and chief billing officer for the University of Illinois Hospital Physicians in Chicago.

Instead, the payer reasons that many of the "component services" that make up the physician's total effort when performing a particular service (such as surgical approach and closure) are already paid as part of the primary procedure. In other words, the multiple-procedure reduction is the payers'way of avoiding redundant charges for shared work under two or more codes.

Typically, payers will reimburse 100 percent of the assigned RVUs for the primary procedure and 50 percent of the assigned RVU value for subsequent procedures (that is, any procedures with modifier -51 appended).

Example: The surgeon performs a multi-code procedure. Code X has a value of $50, code Yhas a value of $40 and code Z has a value of $30. In this case, you should list the highest valued code (code X) without a modifier and bill the subsequent codes with modifier -51, Church says. The payer will reimburse code X at its full value and pay codes Yand Z at 50 percent of their value, for a total of $85 (50 + [40 x .5] + [30 x .5] = 85).

However, if you report a lower-paying code as the primary procedure and append modifier -51 to the highest-paying code, your reimbursement will suffer. For example, if you list code Ywithout a modifier and append -51 to codes X and Z, your payment will total only $80 (40 + [50 x.5] + [30 x .5] = 80), or a loss of $5.

Never append modifier -51 to designated add-on codes (any code listed with a "+") or to modifier -51 exempt codes, such as bone grafts (for example, 20931, Allograft for spine surgery only; structural), Church says. The relative values for these codes already take into account the "additional" nature of the procedure and, as such, payers should not reduce payment for these procedures further under any circumstances.

Check with your individual payers to determine their guidelines for use of modifier -51, Church recommends. Many payers no longer require that you use modifier -51 because they have adopted computerized billing programs that automatically sequence codes according to their RVUs. For these payers, you should skip using modifier -51 for your claims.