General Surgery Coding Alert

When calculating excision diameter, be careful not to confuse the length of the incision with margins. The surgeon may make incisions of varying sizes depending on lesion type and location, as well as the closure method used, but the incision's size should not affect code selection for the lesion.

Often, the physician will make an incision that is longer than the lesion because "the longer you make that ellipse, the flatter your scar is going to be," but this has no bearing on code selection, says Allan Wirtzer, MD, a dermatologist in private practice at Mid-Valley Dermatology in Sherman Oaks, Calif., and the American Academy of Dermatology's representative to the CPT Advisory Committee.

For example, CPT contains an illustration (see Figure 2, below) showing a lesion with margins, as well as an incision in an elongated football shape marked by long dashes. "What CPT is trying to show is that you don't use the size of the ellipse [or football-shaped incision area] when choosing a code," Wirtzer says. Rather, you should determine the size of the lesion (shown in shading at 2.0 centimeters) and the margin (shown in a solid oval of 0.2-cm margins on each side of the lesion) to arrive at a total excision diameter of 2.4 cm, he says.

Payers, fearing that physicians may abuse them and attempt to overcode by stating greater-than-appropriate excision diameters, have expressed some misgivings about the new guidelines for determining lesion excisions. Therefore, Wirtzer reminds physicians to measure and document excision diameters carefully, using a ruler. "Don't try to eyeball it," he says.