Lower Abdominal Bulge after DIEP Flap Breast Reconstruction: Role of the Anterior Rectus Sheath

The etiology of lower abdominal bulge following breast reconstruction with the DIEP flap is uncertain. Most studies report an incidence that ranges from 0.7 to 5%. This is of interest because the rectus abdominis muscle and anterior rectus sheath are not removed with this operation. The purpose of this study was to review a set of factors that may predispose to a lower abdominal bulge and to review the role of the anterior rectus sheath.

This was a retrospective review of 123 women who had breast reconstruction with the DIEP flap over a 4-year period. The reconstruction was unilateral in 93 women and bilateral in 30 women, totaling 153 flaps. Etiologic factors that were evaluated included patient age, diabetes mellitus, tobacco use, previous abdominal operations, unilateral or bilateral reconstruction, previous childbirth, aponeurotic plication to improve the natural abdominal contour, and the use of Marlex mesh.

A lower abdominal bulge occurred in five of the 123 women (4%) and included two following bilateral reconstruction (6.6%), and three following unilateral reconstruction (3.2%). Analysis of the factors for all women demonstrated diabetes mellitus in 0.8%, tobacco use in 5.7%, a prior abdominal operation in 30%, previous childbirth in 77%, aponeurotic plication in 40%, and use of Marlex mesh in 3.3%. Statistical analysis was not significant but did demonstrate a trend for a lower abdominal bulge in women who had not been pregnant (p = 0.08). Fascial attenuation was noted in all women at time of bulge repair. The bulge was repaired by aponeurotic plication and reinforcement with Marlex mesh. In two of two women who had horizontal plication, a persistent lower abdominal bulge was appreciated.

The results of this study demonstrate that certain women may be predisposed to develop a lower abdominal bulge following the DIEP flap. In this study, the bulge was secondary to attenuation of the anterior rectus sheath in all cases. Pregnancy may confer a preventive effect, as the collagen fibers strengthen in order to overcome the stretching forces. Techniques for prevention and treatment include intraoperative assessment of the anterior rectus sheath, use of an adjuvant material for reinforcement, if unstable, and vertical plication for bulge repair.