Study of the arterial pattern of the rectum and its clinical application.

The purpose of this communication was to study rectal arterial supply in order to characterize its various patterns and use them to help avoid rectal ischemic complications and, in addition, to explain some of the unknown rectal pathologic conditions. Thirty-two cadavers were studied. The pelvic organs were eviscerated. The rectal arteries were examined by direct dissection in 12 specimens and after injecting the inferior mesenteric artery with barium sulfate in 20 specimens. The superior rectal artery (SRA) and vein were found to be enclosed in a fibrous sheath which was connected to the posterior rectal surface by an anterior mesorectum containing the "transverse rectal branches', and to the sacrum by an avascular posterior mesorectum. Small lymph nodes were scattered alongside the anterior mesorectum. The SRA gave rise to 4 branches: transverse rectal, descending rectal, rectosigmoid and terminal. The transverse rectal arteries arose from the SRA in 24 specimens and from the descending rectal artery in 8. They were distributed to the upper half of the rectum. The rectosigmoid artery was distributed to the descending limb of the sigmoid colon and rectosigmoid junction. We found 2 terminal branches in 21/32 cadavers and 3 in 11/32. They communicated in the lower half of the rectum. The inferior rectal arteries were present in all the dissected cadavers while the middle rectal arteries could be identified in only 50% of the cadavers. Two arterial patterns were recognized: annular in the upper rectal half provided by the transverse rectal arteries and plexiform in the lower half supplied by the SRA terminal branches.