Extraperitoneal tunneling reduces intraperitoneal drain displacement in rectal cancer surgery: a single-center before-and-after comparative study.

PURPOSE: Anastomotic leakage (AL) is a serious complication of rectal cancer surgery, and a properly positioned pelvic drain may aid early detection and conservative management; however, intraperitoneal drains frequently migrate. We evaluated whether extraperitoneal tunneling (EPT) of the pelvic drain reduces drain displacement compared with conventional intraperitoneal placement. METHODS: This single-center before-and-after comparative study enrolled adults with rectal cancer located within 15 cm of the anal verge who underwent elective radical resection between August 2021 and July 2024. Patients operated between August 2021 and December 2022 received conventional intraperitoneal drains (non-EPT group) and those operated between January 2023 and July 2024 received EPT drains (EPT group). The primary outcome was drain displacement (>3 cm from the anastomotic staple line) on postoperative day 2 plain radiograph. Secondary outcomes were AL, EPT-related complications, and the need for additional intervention. Multivariate logistic regression, propensity score matching (PSM), and inverse probability of treatment weighting (IPTW) were performed. RESULTS: Of 228 patients, 111 received EPT and 117 received conventional drains. Drain displacement occurred in 5 of 111 EPT patients (4.5%) versus 55 of 117 non-EPT patients (47.0%; P<0.001). After multivariate adjustment, EPT was an independent protective factor (adjusted odds ratio [OR], 0.05; 95% confidence interval [CI], 0.02-0.13; P<0.001). The protective association was robust across PSM (matched OR, 0.07; 95% CI, 0.02-0.18) and IPTW (OR, 0.05-0.06; both P<0.001). AL occurred in 6 patients (2.6%) without a significant between-group difference (EPT, 1.8% vs. non-EPT, 3.4%; Fisher exact, P=0.681). Operative time, overall complications, and EPT-related complications did not differ between groups. CONCLUSION: In this single-center before-and-after series, EPT was associated with a substantially lower rate of postoperative day 2 drain displacement after rectal cancer surgery.