An anatomic basis to prevent ischemia of the colon during operations upon the aorta.

According to standard practice, the inferior mesenteric artery, when sacrificed, should always be ligated at its origin, proximal to the left colic branch. However, it should not be sacrificed and ligated but instead, be reimplanted if any doubt exists regarding the adequacy of the collateral circulation. The patient is in a high risk category for development of ischemia of the colon if there is an occlusion or absence of the marginal artery at the splenic flexure; absence of the middle colic artery; occlusion of one or both hypogastric arteries, or enlargement of the left colic artery, suggesting occlusion of the superior mesenteric artery.