During low anterior resection for rectal cancer, the inferior mesenteric artery (IMA) is ligated at its origin. Which artery becomes the principal collateral supply to maintain perfusion of the proximal colon and prevent ischemia at the anastomosis?

• A Middle colic artery via Riolan's arcade (marginal artery of Drummond) ✓
• B Superior rectal artery via the rectal arterial plexus
• C Inferior pancreaticoduodenal artery
• D Iliolumbar artery via retroperitoneal collaterals

Explanation

When the IMA is ligated at its origin, perfusion to the descending and sigmoid colon depends on the collateral pathway from the superior mesenteric artery via the middle colic artery, through Riolan's arcade and the marginal artery of Drummond, to the left colic artery. The superior rectal artery is distal to the ligation and cannot supply the proximal colon. The inferior pancreaticoduodenal artery supplies the duodenum and pancreatic head, not the colon.

Reference: Gray's Anatomy, 42nd ed.

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Written and medically reviewed by the StethoPrep medical team.