Gaps in the Evidence for High Versus Low Inferior Mesenteric Artery Ligation in Rectal Cancer Surgery.

INTRODUCTION: The optimal level of inferior mesenteric artery ligation in rectal cancer surgery remains controversial. This meta-analysis of randomized controlled trials (RCTs) compares clinical and functional outcomes between high ligation (HL), performed at the origin of the inferior mesenteric artery, and low ligation (LL), performed distal to the left colic artery with preservation of the left colic artery. METHODS: Registered with PROSPERO, we systematically searched Embase, PubMed, and Cochrane Library (up to April 2025) for RCTs comparing HL versus LL. Primary outcomes included anastomotic leakage (AL), mean operative time, lymph node yield, 5-y overall survival and disease-free survival, and 1-y fecal incontinence quality of life scores. RESULTS: Analysis of 12 RCTs (1522 patients) suggested that LL may be associated with a lower risk of AL than HL (odds ratio (OR) = 1.65, 95% confidence interval: 1.07-2.54, P = 0.02); however, trial sequential analysis indicated that the cumulative evidence remains insufficient for a definitive conclusion. LL was also associated with improved postoperative bowel function recovery, with a nonsignificant trend toward a shorter time to first flatus (mean difference [MD] = 0.35 d, P = 0.07) and significantly better 1-y fecal incontinence quality of life scores (MD = -1.82 points, P = 0.05), while no significant differences were observed in 5-y overall survival (OR = 1.15, P = 0.65), disease-free survival (OR = 0.93, P = 0.78), or recurrence rates. While HL showed transient intraoperative advantages (shorter operative time: MD = -10.76 min; reduced blood loss: MD = -4.76 mL), no statistically significant difference was observed in lymph node yield (MD = -1.76, P = 0.09). CONCLUSIONS: In rectal cancer surgery, HL and LL appear to achieve comparable long-term oncologic outcomes. Current evidence does not establish a definitive impact of ligation level on AL. LL may offer modest functional advantages, including a trend toward earlier return of bowel function and improved fecal incontinence-related quality of life.