Radiology Coding Alert

Question: Our interventional radiologist often assists during nephrolithotripsy surgery by performing an antegrade pyelogram and dilating a tract through which the urologist removes the patient's kidney stone. Our interventionist recently started assisting in the stone removal. If the stone is larger than one centimeter, can we charge a surgical assistant fee?

California Subscriber
Answer: The answer depends on the size of the kidney stone. If the stone is smaller than 2 cm and you performed the procedure described by code 50080 (Percutaneous nephrostolithotomy or pyelostolithotomy, with or without dilation, endoscopy, lithotripsy, stenting, or basket extraction; up to 2 cm), Medicare will not reimburse your surgical assistant claim.
  According to CMS' 2003 Physician Fee Schedule Relative Value File, 50080 carries a "1" assisted surgery classification, which means that "statutory payment restriction for assistants at surgery applies to this procedure. Assistant at surgery may not be paid."
 
If the kidney stone is larger than 2 cm, you can append modifier -80 (Assistant surgeon) to your claim. The fee schedule assigns a "2" assisted surgery code to 50081 (Percutaneous nephrostolithotomy or pyelostolithotomy, with or without dilation, endoscopy, lithotripsy, stenting, or basket extraction; over 2 cm), which means that "Payment restriction for assistants at surgery does not apply to this procedure. Assistant at  surgery may be paid."
  If the stone exceeded 2 cm, you should coordinate billing with the urologist to ensure that you report the same CPT Codes (the urologist would report 50081, you would report 50081-80) and the same diagnosis codes. Your insurance payer may also require documentation that indicates why your assistance was medically necessary. Most guidelines indicate that assistant surgeons must "actively participate" in the procedure, not simply observe or stand by in case they are needed.
 
Modifier -80 applies to surgeries during which your surgeon acts as the primary surgeon's "extra set of hands." But if the urologist were to encounter an unex-pected problem during the surgery and require your sur-geon's temporary assistance, you would report modifier -81 (Minimum assistant surgeon) instead.
 
According to the September 1992 CPT Assistant , you should choose modifier -81 if "during the operation a minor problem is encountered that requires the service of an assistant surgeon for a relatively short period of time."