LAUSR

Background: Abdominal bulging at the donor site of free abdominal flaps for breast reconstruction is a common postoperative complication. In addition to the thickness of abdominal muscles, the authors identified the rectus abdominis diastasis as an important factor that compromises abdominal wall strength. This study aimed to assess the relationship between preoperative abdominal wall strength and postoperative abdominal bulging. Methods: A total of 224 patients were enrolled in this study. Patient demographics, the rectus and lateral abdominis muscle thicknesses, and the rate of rectus abdominis diastasis were compared (with versus without bulging). Muscle thickness and rectus abdominis diastasis were investigated by preoperative computed tomography. Results: The group with bulging consisted of 32 patients (14.3 percent), whereas the group without bulging consisted of 192 patients. The group with bulging had a significantly higher gestational history rate. The thickness of the rectus abdominis muscle in the group with bulging was significantly thinner (median, 8.6 mm versus 10.5 mm; p < 0.001) and the rate of rectus abdominis diastasis was significantly higher (78.1 percent versus 32.3 percent; p < 0.001). There were no significant differences with respect to the thickness of the lateral abdominal muscle and the other factors (i.e., age, body mass index, history of laparotomy. and operative details). Conclusions: Because the diagnosis of abdominal bulging was based on severity, the rate may be high compared to that reported from previous studies. Because the factor of gestational history correlated to thickness of the rectus abdominis muscle and rectus abdominis diastasis, this factor influenced the occurrence of abdominal bulging. Patients with a thin rectus abdominis muscle and rectus abdominis diastasis were at higher risk of abdominal bulging. CLINICAL QUESTION/LEVEL OF EVIDENCE: Risk, III.