Radiographic Study Evaluating Perforator Vessels in the Ischiorectal Fossa for Safe Elevation of Island Flaps

Background: Perforator flaps based on the ischiorectal fossa (IRF) (ie, internal pudendal artery perforator flaps) are useful for perineal reconstruction. The three-dimensional characterization of perforator arteries in the IRF remains unclear, as the IRF contains thick adipose tissue as well as organs, such as the rectum, vagina, and urethra. This study aimed to evaluate perforators in the IRF to guide the safe elevation of skin flaps designed based on the IRF. Methods: IRF vessels were examined in 200 bilateral computed tomography angiography scans performed in 100 patients. We examined branching patterns arising from the internal iliac artery and the origins of the skin perforators in the IRF. Results: The branching patterns of the internal iliac artery were divided into three groups: perforators derived exclusively from the internal pudendal artery (78%), perforators derived from the internal pudendal artery and the inferior gluteal artery (18%), and perforators derived exclusively from the inferior gluteal artery (4%). The average number of perforators in the IRF was 1.5 ± 0.7. The number of perforators was significantly higher in women than in men. The perforator arteries were found exclusively around the medial and dorsal sides of the ischial tuberosity. Conclusions: We found that perforators in the IRF were stable. All cases had more than one skin perforator, which was mainly derived from the internal pudendal artery. Although perforators cannot be identified during flap elevation because the fatty tissue in the IRF is very thick, physicians must focus on preserving the perforator-containing fatty tissue around the ischial tuberosity.