Extra-Peritoneal Tunneling Versus Conventional Drain Fixation After Anterior or Low Anterior Resection

resection for rectal cancer. Although prophylactic pelvic drainage has been widely used to detect early leakage and to prevent pelvic sepsis, recent randomized trials and meta-analyses have reported that routine drain placement provides no significant benefit in reducing postoperative morbidity. One possible reason is drain displacement, which occurs in up to 30-40% of cases, resulting in the drain being positioned far from the anastomotic site and losing its intended function.

The extra-peritoneal tunneling (EPT) drain fixation method is a new surgical technique designed to prevent drain displacement by creating an extraperitoneal tunnel that anchors the drain securely near the anastomosis. This technique is performed using the Drain-TG™ (DTG) device developed by JSR Medical (Daegu, Korea). Preliminary retrospective data have shown that the EPT technique dramatically reduces drain displacement (2.8% vs. 40% with conventional insertion, p \< 0.001) and that, in patients who developed AL, the success rate of conservative management (drain maintenance and antibiotics only) exceeded 80%, compared with 43% in the conventional group.

The ExPeTuD trial is a prospective, multi-center, randomized controlled trial that aims to establish strong evidence for the efficacy and safety of the EPT drain fixation method. Patients undergoing anterior or low anterior resection with a predicted anastomosis ≤ 10 cm from the anal verge will be enrolled from approximately 20 tertiary hospitals across Korea. Participants will be randomized 1:1 to either the EPT group or the conventional drain group, stratified by sex, tumor level (above vs. below the peritoneal reflection), and preoperative chemoradiation status.

The primary outcome is the success rate of conservative management (drain maintenance and/or antibiotics) for AL according to drain insertion method. Secondary outcomes include:

Rate and timing of drain displacement (defined as \> 3 cm separation from the anastomotic site on X-ray),

Drain-related complications (infection, pain, bleeding, or organ injury),

Time to diagnosis of AL and time to re-intervention,

Postoperative recovery outcomes such as ileus, hospital stay, and overall morbidity (Clavien-Dindo classification).

Radiologic monitoring (abdominal X-rays on postoperative days 2, 4, and 6) will be performed to assess drain position, and additional imaging will be conducted if AL is suspected. Standard postoperative care, including enhanced recovery after surgery (ERAS) protocols, will be applied equally to both groups.

A total of 596 participants (298 per arm) will be recruited, which accounts for an expected 6% AL rate after low anterior resection and ensures sufficient power for superiority testing. Interim analysis will be conducted once ≥ 9 AL events occur in each group to assess safety and trial feasibility.

If the EPT drain fixation method proves effective in maintaining drain position and improving conservative management success rates, it could reduce the need for reoperation, shorten hospital stay, and improve patient outcomes after rectal cancer surgery. This trial aims to provide robust clinical evidence supporting the adoption of the EPT technique as a standard method for pelvic drainage following proctectomy.

• Incidence of drain displacement according to drain fixation method [Time frame: Up to drain removal, an average of 7 days]
• Time to drain displacement (days) [Time frame: Up to drain removal, an average of 7 days]
• Incidence and types of drain-related complications according to drain fixation method [Time frame: Up to drain removal, an average of 7 days]
• Early detection of anastomotic leak (days from surgery to diagnosis) [Time frame: Time to anastomotic leak, assessed up to 90 days after surgery]
• Interval between anastomotic leak diagnosis and reoperation (hours) [Time frame: Time from leak diagnosis to reoperation, assessed up to 30 days after leak diagnosis]