Inferior mesenteric artery morphology and its branching variations: a meta-analysis of 9358 patients with implications for colorectal surgery

The inferior mesenteric artery (IMA) is a crucial artery that supplies the colon and rectum. As colorectal cancer is most commonly localized in the descending and sigmoid colon, as well as in the rectum, detailed knowledge of the anatomy of the IMA is of utmost importance for oncological surgeons performing hemicolectomies. An extensive search of major databases was performed up to April 2026 for studies detailing the morphometry, anatomy, and variations of the IMA. The study strictly adhered to the PRISMA guidelines. Out of 143,884 initial records, 66 original studies met the inclusion criteria. A random effects model was applied in the statistical analyses, and heterogeneity was evaluated using Chi-squared and I -squared statistics. The IMA most often originated at the L3 vertebral level (60.35%). The number of sigmoid arteries varied across the study groups, with 2 sigmoid arteries variant being the most common variant at 38.42%, followed by 3 sigmoid arteries variant at 31.30%. Across IMA branching pattern classification systems, the most prevalent anatomical variations were Type 1 in the modified Yada scale (47.39%), Type 1 in Latarjet scale (47.39%), Type 1B in McSweeney scale (45.51%), and Type B in modified Zebrowski scale (20.35%). To standardize complex branching patterns, we propose supplementing the modified Yada scale with the exact number of sigmoid arteries for clinical practice, while recommending the McSweeney scale for prospective research. Surgeons must account for significant anatomical variability, as IMA originates at the L3 level in only 60.42% of cases, and the number of sigmoid arteries varies widely, most commonly presenting as two or three. Ultimately, accurate preoperative visualization and standardized IMA categorization are crucial for optimal surgical outcomes.