Volume change in the rectus abdominis muscle after deep inferior epigastric perforator flap harvest

Deep inferior epigastric perforator (DIEP) flap is associated with less donor site morbidity than transverse rectus abdominis myocutaneous flap. However, abdominal muscle atrophy and donor site complications caused by denervation during pedicle dissection cannot be avoided. This retrospective study investigated the change in the rectus abdominis muscle volume after DIEP flap harvest. Of 395 patients who underwent unilateral DIEP flap breast reconstruction between August 2007 and July 2017, 25 patients with >2-year postoperative abdominal computed tomography data were evaluated. Preoperative and postoperative images of the abdominal muscle after pedicle dissection and the nonoperated side were compared. The volume of the muscles from the lower margin to the umbilicus was determined by using OsiriX image analysis application. The muscle volumes on the side of pedicle dissection decreased from 72.63 ± 23.29 cm³ preoperation to 53.09 ± 16.93 cm³ postoperation (p < 0.001). The corresponding volumes on the side without dissection were 73.29 ± 19.25 cm³ and 60.89 ± 18.79 cm³ (p < 0.001). The percentage of postoperative retained volume relative to the preoperative retained volume was 75.65% ± 19.18% on the pedicle dissection side and 84.65% ± 19.00% on the contralateral side. The 9% difference was not statistically significant (p = 0.10). No major abdominal complications were observed. Despite nerve injury during DIEP flap surgery, the volume loss of the involved and contralateral muscles did not differ. More than 75% of the abdominal muscle volume was retained. Muscle integrity was well maintained without any postoperative complications.