The anatomy of lateral ligament of the rectum and its role in total mesorectal excision.

Background: Lateral ligament of the rectum has suffered many diverse descriptions in its existence and composition. This study was undertaken to define the anatomy, nature, content of the lateral ligament of the rectum, and its role in total mesorectal excision.

Methods: Cadaver dissections were performed on 32 formalin-preserved cadavers.

Results: Bilateral lateral ligament appeared in all 32 cadavers as a bundle of dense connective tissue traversing between rectum and visceral fascia instead of pelvic sidewall. No substantial tissue strand except pelvic splanchnic nerves was found between visceral fascia and parietal fascia at the same level. The middle rectal artery was observed in only 18 of 64 pelvic-halves (28.1%). The constant component of the lateral ligament of the rectum was the rectal branches from the pelvic plexus, whereas the middle rectal artery was almost invisible in lateral ligament of the rectum.

Conclusions: During total mesorectal excision, it is impossible to reveal the lateral ligament of the rectum in the correct plane between visceral and parietal fascia. The entire rectum may be mobilized without the need for ligating the middle rectal artery. The clinical significance of lateral ligament is that, during lateral dissection, if the dense lateral ligament was identified, then the surgical plane was medial to the visceral fascia and incorrect surgical plane thus entered.