OBJECTIVETo further understand the anatomical basis of pelvic autonomic nerve preservation.

METHODSAutopsy of five adult male donated cadavers was performed. Meanwhile, ten videos of laparoscopic total mesorectal excision for male mid-low rectal cancer admitted from January to June 2012 were observed and studied. Anatomical features of pelvic autonomic nerve were compared between autopsy and laparoscopic appearance.

RESULTSAutopsy observations indicated that:the abdominal aortic plexus was situated upon the sides and front of the aorta, between the origins of the superior and inferior mesenteric arteries. The superior hypogastric plexus was a plexus of nerves situated on the the bifurcation of the abdominal aorta to sacrum; after incision of sacrum fascia was done cling to the sacrum; the pelvic splanchnic nerves and sacral splanchnic nerves were demonstrated; pelvic splanchnic nerves were splanchnic nerves that arised from ventral rami of the second, third, and often the fourth sacral nerves to provide preganglionic parasympathetic innervation to the hindgut;sacral splanchnic nerves providing postganglionic fibers, emerged from the sympathetic trunk, were then joined by the pelvic splanchnic nerves to form the inferior hypogastric plexuses which were placed lateral to the rectum.Laparoscopic observations showed that:abdominal aortic plexus and superior hypogastric plexus were unclear; at the level of sacroiliac joint, the hypogastric nerve began where the superior hypogastric plexus split into a right and left plexus, situated under the loose connective tissue, and continued inferiorly on its corresponding side of the body at the level of the 3rd sacral vertebra;left hypogastric nerve was closed to posterior of mesorectum;denonvilliers fascia was thin, reflective fascial structure, and easily removed together with mesorectum excision because of anterior loose structure.

CONCLUSIONSLigation of the inferior mesenteric artery at its origin is safe.Excessive dissection of the connective tissue covering the surface of the aorta should be avoided to protect the abdominal aortic plexus.Sharp dissection performed by pursuing the outer surface of the mesorectum maintaining the integrity of mesorectum, could avoid the superior hypogastric plexus and hypogastric nerves injury posteriorly, and protect the inferior hypogastric plexues while cutting lateral ligament laterally. The integrity of Denonvilliers fascia during anterior resection of rectum should be confirmed to avoid urogenitalis aparatus branches damage.