Objective To investigate the effect of ligation methods of inferior mesenteric artery (IMA) on preserving left colic artery (LCA) in laparoscopic radical resection of rectal cancer.

Methods The prospective randomized controlled study was conducted. The clinical data of 864 patients who underwent laparoscopic radical resection of rectal cancer at Renji Hospital of Shanghai Jiaotong University School of Medicine from January 2020 to December 2024 were selected. Patients were randomly divided into the low ligation group and high ligation group using a random number table. Patients of the low ligation group underwent laparoscopic radical resection of rectal cancer with preserving LCA by low ligation of IMA and apical lymph node dissection, and patients of the high ligation group underwent laparoscopic radical resection of rectal cancer with traditional high ligation of IMA. Observation indicators: (1) grouping of the enrolled patients; (2) intraoperative conditions; (3) postoperative pathological examination; (4) postoperative recovery. Comparison of measurement data with normal distribution between groups was conducted using the independent sample t test. Comparison of count data between groups was conducted using the chi‑square test or Fisher exact probability. Comparison of ordinal data between groups was conducted using the non-parametric test.

Results (1) Grouping of the enrolled patients. A total of 864 patients with rectal cancer who underwent laparoscopic radical resection of rectal cancer were screened for eligibility, including 410 males and 454 females, aged (63±11)years. All 864 patients were randomly divided into the low ligation group and high ligation group, with 432 patients in each group. There was no significant difference in gender, age, body mass index, carcinoembryonic antigen, distance from tumor to anal margin, diabetes, hypertension, neoadjuvant radiochemotherapy, IMA subtypes and IMA length between the two groups (P>0.05), ensuring comparability. (2) Intraoperative conditions. All patients of the two groups successfully completed surgery, with no errors in blood vessel ligation during operation or conversion to open surgery. There was a significant difference in time of IMA dissection between the low ligation group and high ligation group (31±11)minutes vs. (28±9)minutes, t=4.39, P<0.05, and there was no significant difference in total operation time, volume of intra-operative blood loss or prophylactic stoma rate between the two groups (P>0.05). (3) Postopera-tive pathological examination. There was a significant difference in the number of lymph node dissected between the low ligation group and high ligation group (1.8±1.4 vs. 1.5±1.4, t=2.51, P<0.05), and there was no significant difference in tumor diameter, the total number of lymph node dissected, total lymph node positive status, No.253 lymph node positive status, TNM staging between the two groups (P>0.05). (4) Postoperative recovery. The time to postoperative first flatus and the number of anastomotic leakage of patients in the low ligation group were (74±22)hours and 16 cases, versus (78±20)hours and 31 cases in the high ligation group, respectively, showing significant differences in the above indicators between the two groups (t=2.52, χ²=5.06, P<0.05). There was no significant difference in the time to postoperative initial liquid food intake, duration of post-operative hospital stay, duration of abdominal drainage tube indwelling, duration of anal tube indwelling, postoperative wound infection, pulmonary infection, intestinal obstruction, or urinary dysfunction between the two groups (P>0.05). None of patients in the two groups had readmission or death during the postoperative 30 days.

Conclusion Low ligation of IMA in laparoscopic radical resection of rectal cancer can guide precise LCA preservation, which is beneficial for accelerating the recovery of intestinal function and reducing the incidence of anastomotic leakage.