Regional differences in ultrasonic assessment of subcutaneous fat thickness in the abdomen: effects on the TRAM flap.

The authors describe the results of fat thickness patterning of the abdominal sites in 50 patients, all of whom required breast reconstruction with a transverse rectus abdominis musculocutaneous flap. The thickness of the abdominal fat was measured at 12 anatomic locations with an ultrasonic instrument. The highest value of the subcutaneous fat thickness was 29.0+/-10.0 mm at a site 2 cm below the umbilicus at the center of the rectus abdominis muscle. The lowest value of the subcutaneous fat thickness was 17.8+/-7.6 mm at a site 2 cm above the umbilicus on the anterior superior iliac spine. Average subcutaneous fat thickness over the abdomen of 50 patients was 24.0+/-9.4 mm. There were 13 patients (group 1) who had an abdominal fat thickness of more than 30 mm, 19 patients (group 2) with an abdominal fat thickness less than 30 mm and more than 20 mm, and 18 patients (group 3) with an abdominal fat thickness less than 20 mm. Complications occurred in 12 of 50 flaps (24%). Among groups 1, 2, and 3 there was no significant difference (p<0.01) in the overall flap complications (15.4: 36.8: 16.7). In summary, subcutaneous fat thickness showed the higher value at the center of the abdomen and the lower value at the lateral site. Abdominal fat thickness is not a risk factor for necrosis of pedicled transverse rectus abdominis musculocutaneous flaps in patients who are thin, average, or mildly obese. Preoperative examination of the abdominal subcutaneous fat thickness should provide useful information for detailed simulation of a reconstructive operation.