Fat necrosis in deep inferior epigastric perforator flaps: an ultrasound-based review of 202 cases.

Background: In autologous breast reconstruction after mastectomy, fat necrosis is a rather common complication that may lead to secondary corrective surgery. The understanding of fat necrosis until now has been limited because previous studies were based exclusively on physical examination and used diverse definitions. Methods: The authors retrospectively reviewed the incidence of fat necrosis and the correlation of several risk factors in 202 deep inferior epigastric perforator (DIEP) flaps for breast reconstruction. The incidence of fat necrosis was based on both physical examination and ultrasound imaging. The following risk factors were studied: age, smoking, body mass index, timing of reconstruction, and timing and extent of radiation therapy fields. Results: Physical examination revealed a palpable mass or nodule in 14 percent of the DIEP flaps (28 of 202). Ultrasound examination added another 21 percent of DIEP flaps (42 of 202) with a firm area of scar tissue (diameter >= 5 mm). The overall ultrasound incidence of fat necrosis in this study was 35 percent (71 of 202). Although the overall ultrasound incidence of fat necrosis was very high, only 7 percent of the DIEP flaps (15 of 202) needed to undergo an extra surgical procedure for removal of this area. In contrast to previous studies, none of the risk factors studied was statistically significant for the occurrence of fat necrosis. Conclusions: These results suggest that there is no significant association between previously suspected risk factors and fat necrosis. The overall incidence of fat necrosis, however, is much higher than previously accepted, even though the need for corrective surgery is limited. (Plast. Reconstr. Surg. 124: 1754, 2009.)