[Comment] Impact of low ligation on bowel perfusion and anastomotic leakage in minimally invasive rectal cancer surgery: a post hoc analysis of a randomized controlled trial

[Background] Whether the level of the inferior mesenteric artery ligation affects the incidence of anastomotic leakage remains unclear. [Objective] To assess the impact of the level of inferior mesenteric artery ligation on the blood flow to the anastomotic site and the incidence of anastomotic leakage using indocyanine green fluorescence imaging. [Design] A post hoc analysis of EssentiAL trial. [Settings] This study was conducted at 41 tertiary referral centers in Japan. [Patients] 839 rectal cancer patients (<12 cm from the anal verge). [Main outcome measures] The incidence of anastomotic leakage and perfusion status were compared between the high and low ligation groups. [Results] The median fluorescence time was similar at 25 seconds in both groups (P=0.74). Although no statistical difference was noted, the high ligation group was more likely to have greater outliers in fluorescence time compared to the low ligation group. The high ligation group demonstrated higher poor perfusion rates than the low ligation group (2.8% vs. 1.5%, P=0.52). In the high ligation group, anastomotic leakage occurred in one case of poor perfusion where additional resection was not performed by the surgeon’s intraoperative judgment. Additionally, the additional resection rate nearly doubled with the use of indocyanine green fluorescence imaging. After propensity score matching (129 patients per group), the overall anastomotic leakage rate was 13.2% in the high ligation group and 10.9% in the low ligation group (P=0.57). Limitations This study was a post hoc analysis, the sample size was small, and the anastomosis methods varied. [Conclusions] The level of inferior mesenteric artery ligation did not affect blood flow at the anastomotic site or the incidence of anastomotic leakage statistically, but assessing bowel perfusion using indocyanine green fluorescence imaging can offer clinical benefits, optimizing patient outcomes. [Trial registration] The Japan Registry of Clinical Trials (jRCTs-CRB3180007), the Japanese Clinical Trials Registry (UMIN-CTR000030240).