Fat and lymphatic tissue are removed from 1 cm downward from the root of the inferior mesenteric artery. The inferior abdominal nerve was free in the angle between the abdominal aorta and the inferior mesenteric artery, and was held in a sling for protection, and then the connective tissue around the abdominal aorta and inferior vena cava was removed from above. At the bifurcation of the left and right common iliac arteries, the inferior abdominal nerve was divided into two branches, left and right, which were held in a sling for protection, and then cleared of both common iliac and external iliac arteries and the deep inguinal lymph nodes and adipose tissue. The left and right branches of the inferior abdominal nerve traveled downward to the anteromedial aspect of the internal iliac artery, which was freed and lifted for protection, and the lymph and adipose tissue adjacent to the internal iliac and foramen ovale arteries were cleared. At the height of S2, some patients can see the pelvic visceral nerve originating from S2 on the lateral side of the internal iliac artery, and the lymphatic and adipose tissue around this nerve is cleared. It is not easily damaged because of its location too deep. Identify the pelvic plexus, which is composed of the pelvic visceral nerve and the inferior abdominal nerve together, and is located anteromedial to the internal iliac artery in a parallelogram-like sieve. Protect this plexus and remove the connective tissue between it and the internal iliac artery. Thoroughly remove the connective tissue surrounding the inferior abdominal nerve. Thoroughly remove the connective tissue from the surface of the pelvic plexus and go straight down to the anal raphe. Close to the rectum, the anterior rectal wall is freed anterior to Denonvilliers fascia. The branches of the pelvic plexus that innervate organs other than the rectum are preserved as much as possible, and the lateral walls of the rectum are freed by severing the ligaments on both sides of the rectum outside the proximal pelvic wall (preserving the nerve branches is quite difficult because they are particularly slender, which may be the reason why sometimes the nerves are preserved but the functional improvement is less than optimal).