Localisation of hypogastric nerves and pelvic plexus in relation to rectal cancer surgery

Urinary, bowel, and sexual dysfunction caused by iatrogenic lesions of the pelvic plexus remain a common complication of radical pelvic surgery. Preservation of these nerves during surgery is hampered by their poor visualisation within the pelvic cavity and their small size. Recently, increased awareness of the high incidence of post-operative autonomic dysfunction has led to the development of nerve-sparing surgical techniques. This study aims to expand our knowledge of the anatomy of the pelvic plexus, to contribute to further enhancement of nerve sparing surgical techniques. Dissections of the hypogastric nerves and pelvic plexuses were performed on 10 cadavers. We showed that nerves from the pelvic plexus that supply the rectum can be mobilised to a length of 10-15 mm and thus can be identified and safely divided, leaving the pelvic plexus intact following the extrafascial excision of the rectum. Likewise, the hypogastric nerves, which are enveloped in a layer of parietal fascia, also remain intact. The fascia containing the hypogastric nerves was separated from the fascia propria by a loose areolar layer. Pelvic plexuses measured about 30 by 30 mm in size. Radiological images showed the plexuses to be positioned about 5 mm below a line joining the upper surfaces of two acetabula. This study shows that extrafascial excision does not damage the hypogastric nerves or the pelvic plexuses and provides a way to radiologically assess the proximity of a tumour to the pelvic plexus. Such knowledge aids in preoperative planning to reduce the incidence of post-operative pelvic autonomic dysfunction.