An assessment of the anatomical relationship between the pelvic plexus and the rectal wall to determine the indications for its preservation in surgery for rectal cancer.

Preservation of the pelvic plexus in surgery for rectal cancer could shorten the distance between the cancer and the lateral resection margin, whereby the curability of the operation may be reduced. To clarify the indications for preserving the pelvic plexus in such surgery, the relationship of the pelvic plexus to the rectum and rectal cancer was investigated anatomically in 12 autopsied specimens and 12 surgical specimens. The rectum and anus were dissected with all the pelvic organs from autopsied cadavers and transverse sections were prepared at 10-mm intervals after fixation. The location of the pelvic plexus was then measured on the tissue preparations, and compared to that of surgical specimens from rectal cancers with concurrent resection of the pelvic plexus. The pelvic plexus was located from 3.3 +/- 1.2 cm above to 2.3 +/- 1.9 cm below the peritoneal reflection in the autopsied specimens. The average distances between the muscularis propria and the pelvic plexus in the autopsied specimens and surgical specimens were 8.3 +/- 3.5 mm and 14.7 +/- 4.5 mm, respectively, showing a significant difference (P < 0.05). Pelvic plexuses were located about 10 mm from the outer margin of rectal muscularis propria. These findings indicate that concurrent resection of the pelvic plexus may be required to secure sufficient surgical clearance in pT3 rectal cancers, especially those invading deeply beyond the muscularis propria (a2).