General Surgery Coding Alert

To assign the required fourth and fifth digits for diagnosis category 948.xx, you must apply the so-called "rule of nines" set forth in ICD-9. The rule of nines divides the body into nine general areas and assigns a percentage value (of 9 or 18 percent) to each, as follows:

 9 percent - head and neck
 9 percent - upper back
 9 percent - lower back
 9 percent - upper front
 9 percent - lower front 
 9 percent - left arm
 9 percent - right arm
 18 percent - left leg
 18 percent - right leg

 
The nine areas total 99 percent, with the remaining 1 percent assigned to the perineum (genitals).
 
The above percentages are slightly different for babies, due to the relative large size of their heads (18 percent). While back and front remain at 18 percent and arms remain at 9 percent, the guidelines trim the legs to 14 percent each to account for the increased size of the head and face.
 
You must determine the affected body areas using the burn location and degree to select codes from the 940-947 series. For example, if the surgeon notes second-degree burns only on the left arm, you will report 943.xx (with fourth and fifth digits as appropriate) and further calculate that the rule of nines assigns a value of 9 percent to the left arm. You should therefore choose a secondary diagnosis of 948.00 (Burn [any degree] involving less than 10 percent of body surface, with third-degree burns of less than 10 percent or unspecified).
 
In a second example, the patient has burns of the front upper torso, as well as the face and left leg, with third-degree burns on both the torso and left leg. When determining the secondary diagnosis (948 series), you add together the values assigned to each body part (9 percent head and neck, 9 percent upper torso, 18 percent left leg) to arrive at a total of 36 percent. Using the same method, calculate the area affected by third-degree burns (9 percent upper torso and 18 percent left leg, for a total of 27 percent). Once you have determined these values, you consult ICD-9 to arrive at a final diagnosis of 948.32 (i.e., burns involving 30-39 percent of body surface, with third-degree burns involving 10-29 percent of the body surface).
 
You should claim the total percentage assigned to a specific body area even if the entire area does not have burns, says Marty Herman, MD, FAAP, FACEP, associate professor of pediatrics at UT College of Medicine, Memphis, Tenn. In other words, if only a portion of the right leg is burned, you should claim the full 18 percent for that area. In the first example above, for instance, the patient may have burns on the forearm only, but you nonetheless count the full 9 percent when determining the proper diagnosis.