Inferior mesenteric artery dominance in colonic blood supply: a cadaveric case report.

PURPOSE: This case report investigates a rare colonic arterial variant where the superior mesenteric artery (SMA) lacks the right colic artery (RCA) and middle colic artery (MCA), with these arising from the inferior mesenteric artery (IMA) via the Meandering Artery of Moskowitz (MAM). It explores surgical implications and classification challenges of such collaterals.

METHODS

An elderly South Asian female cadaver was dissected at the Department of Anatomy, Faculty of Medicine, University of Peradeniya, Sri Lanka. The SMA and IMA branching patterns and anastomotic networks were analysed through direct observation, precise measurements, and photographic documentation. Ethical approval was secured with an exemption from the institutional Ethics Review Committee (Protocol No: 2023/EC/72).

RESULTS

The SMA, devoid of RCA and MCA, supplied only the terminal ileum, cecum, appendix, and proximal ascending colon via the ileocolic artery. The IMA gave off the left colic artery (LCA) which split into two branches. The left branch perfused the descending colon, while the right, identified as the MAM, ran along the inferior mesenteric vein, passed beneath the ligament of Treitz, and bifurcated into the MCA and RCA. These were integrated into the marginal artery of Drummond along with an accessory LCA from the sigmoid trunk. The arc of Riolan was absent, and a persistent descending colon mesentery was observed.

CONCLUSIONS

This anomaly demonstrated the IMA compensating the limited SMA supply through the MAM, which altered watershed zones. Such variations may increase the risk of surgical ischemia with preoperative imaging required to optimize surgical outcomes.