Anatomical basis of autonomic nerve-preserving total mesorectal excision for rectal cancer.

Total mesorectal excision with autonomic nerve preservation for rectal cancer is based on the anatomy of the mesorectum and of the pelvic autonomic nerves. Cadaver dissections were performed to describe the relationship between these structures. Between the rectum and the sacrum a retrorectal space can be developed, lined anteriorly by the visceral leaf and posteriorly by the parietal leaf of the pelvic fascia. The hypogastric nerve runs anterior to the visceral fascia, from the sacral promontory in a laterocaudad direction. The splanchnic sacral nerves originate from the sacral foramina, posterior to the parietal fascia, and run caudad, laterally and anteriorly. After piercing the parietal layer of the pelvic fascia, approximately 4 cm from the midline, the sacral nerves run between a double layer of the visceral part of the pelvic fascia. The relationship between the hypogastric nerves, the splanchnic nerves and the pelvic fascia was comparable in all six specimens examined.