Periportal Right Colic Artery Arising From the Ventral Aspect of the Superior Mesenteric Artery With Associated Vascular Anomalies: A Case Report

The right colic artery (RCA) classically arises from the right convex surface of the superior mesenteric artery (SMA), crossing the superior mesenteric vein (SMV) anteriorly or posteriorly. We report a previously undescribed combination of three concurrent vascular anomalies identified during routine cadaveric dissection: an RCA arising from the ventral SMA surface with a periportal course producing visible indentation of the anterior SMV wall; an aberrant middle colic artery (MCA) arising from the ventral-left SMA surface with immediate bifurcation into right and left branches, the latter running along the inferior pancreatic border; and bifid middle colic venous drainage without a common trunk, with left tributaries draining to the splenic vein and right tributaries draining independently to the SMV. The periportal RCA lies directly within the D3 (third level lymph node dissection) field, the central lymphadenectomy zone extending from the ileocolic artery (ICA) root to the MCA root along the SMA, where the surgeon skeletonizes the SMV and ligates colic vessels at their origins during laparoscopic right hemicolectomy with complete mesocolic excision (CME) and central vascular ligation (CVL). Unlike a standard anteriorly crossing RCA, which maintains a tissue plane between itself and the SMV, this periportal variant contacts the anterior SMV wall directly at the outset of central dissection, creating an unannounced risk of inadvertent SMV laceration during the medial-to-lateral approach. The independent venous drainage to the splenic vein cannot be controlled by standard middle colic vein (MCV) ligation. Preoperative high-resolution computed tomography colonography-angiography (CTC-A) is essential for anticipating such variants. This case demonstrates that right colonic vascular anomalies may occur in complex combinations affecting both the arterial and venous systems. Detailed preoperative vascular mapping is strongly recommended before complete mesocolic excision/central lymphadenectomy to minimize the risk of catastrophic intraoperative hemorrhage.