Colon Perforation Caused by a Transanal Drainage Tube After Robot-Assisted Low Anterior Resection: A Case Report

Transanal drainage tubes (TDTs) are commonly used after low anterior resection to reduce intraluminal pressure around the anastomosis. Although associated complications are usually minor, bowel perforation related to TDT placement is exceedingly rare. We report the case of a 71-year-old man who underwent robot-assisted laparoscopic low anterior resection for rectal cancer. A TDT was inserted intraoperatively, and its position was adjusted under laparoscopic guidance. Abdominal radiography performed on postoperative day (POD) 1 showed that the tube tip was located approximately 7 cm proximal to the anastomosis. On POD 4, the patient developed abdominal pain and signs of peritonitis. Computed tomography demonstrated free air and localized fluid collection near the tube tip. Anastomotic leakage or TDT-induced bowel perforation was suspected, and emergency reoperation was undertaken. Laparoscopic exploration confirmed that the TDT had penetrated the colon wall proximal to the anastomosis, resulting in a perforation. Primary suture repair of the perforation and creation of a diverting loop ileostomy were performed. The postoperative course was uneventful, and the patient recovered without further complications. This case highlights an uncommon but serious complication associated with TDT placement and underscores the importance of meticulous intraoperative positioning, close postoperative monitoring, and prompt evaluation when unexpected abdominal symptoms arise.