Background Several studies have described the structure of the pelvic cavity; however, there is still confusion about the optimal dissection plane of rectal surgery. The aim of this study was to clarify the anatomical structures of the pelvic cavity and identify the correct surgical plane for rectal cancer based on the peritoneum retreat theory. Methods Surgical videos of 29 male patients who underwent laparoscopic operations for rectal cancer were reviewed to identify the anatomical structures of the mesorectum and its surrounding fasciae. Schematic diagrams and sectional illustrations of the pelvic cavity were generated to illustrate its anatomical structures. Results The general anatomy of the pelvic cavity could be divided into three layers (pelvic wall, urogenital system, and rectum) and two interlayers (transversalis fascia and extraperitoneal fascia). The urogenital system layer was an independent viaduct-like structure sandwiched between the pelvic wall and the rectum. The rectosacral fascia was the lower part of the urogenital system layer and was separated from the fascia propria of the rectum by the junction of transversalis fascia and extraperitoneal fascia at the level of S3/4 vertebrae. Posterolateral to the upper rectum, the presacral fascia and posterior renal fascia defined the presacral space, while the anterior renal fascia (also called Gerota's fascia/prehypogastric nerve fascia) and the fascia propria of the rectum defined the retrorectal space. Behind the lower rectum, the presacral fascia and the fascia propria of the rectum defined the supralevator space. Denonvilliers’ fascia in front of the rectum was continuous with the pre-hypogastric nerve fascia. Denonvilliers’ fascia and the fascia propria of the rectum in the front defined the prerectal space. Conclusion The rectosacral fascia is continuous with the urogenital system layer and not directly connected to the posterior rectal wall. The retrorectal, supralevator, and prerectal spaces form the correct surgical plane for mesenteric-based rectal surgery by operating within the extraperitoneal fascia.
Chen et al. (Thu,) studied this question.