Neurosurgery Coding Alert

Question: I notice CPT includes a modifier (-51) for "multiple procedures." I never append this modifier when reporting multiple codes (such as same-day diskectomy and arthrodesis) and have never had difficulties with the payer. Am I facing a possible audit?

Pennsylvania Subscriber

Answer: Many payers, including most Medicare carriers, use software that automatically detects secondary procedures and reimburses them accordingly, thereby making modifier -51 (Multiple procedures) unnecessary. You should check with your individual payer for its guidelines and, as always, request the payer's instructions in writing.
 
If your payer does require modifier -51, you must consider several factors before appending it.
 
For example, you should not use modifier -51 with any codes notated in CPT with a "" or "+" (these codes are also listed in appendix "E" of CPT). Such codes are "modifier -51 exempt" because the relative value units assigned to them already take into account their status as "additional" procedures. 
 
Also, because payers reduce fees for "subsequent" procedures, you should always choose the highest-valued code as the primary procedure and attach modifier -51 to the lesser-valued procedure(s).
 
For example, if the surgeon performs diskectomy (63075, Diskectomy, anterior, with decompression of spinal cord and/or nerve root[s], including osteo-phytectomy; cervical, single interspace) and arthrodesis (22554, Arthrodesis, anterior interbody technique, including minimal diskectomy to prepare interspace [other than for decompression]; cervical, below C2) during the same surgical session for spinal repair, you would report 63075 and 22554-51. Documentation must support medical necessity for each code independently.
 
In this case, you should append modifier -51 to 22554 because it is the lesser-valued procedure. The payer should reimburse 63075 at full value and pay for 22554 at a reduced rate (usually 50 percent of the standard fee).