Postoperative irrigation-suction drainage after pelvic colonic surgery. A prospective randomized trial. A 2-year randomized prospective clinical trial was undertaken to determine whether postoperative irrigation of the pelvis would result in a decreased incidence of local septic complications. Two hundred consecutive patients undergoing low pelvic procedures with rectal resection and entry of the presacral space by a single surgeon, were randomized. In the irrigation group, two of four presacral sump drains were placed to low intermittent suction and the remaining sumps infused continuously with saline until the effluent was clear. In the drainage alone group, all four presacral sump drains were placed to suction. Drains were removed when drainage was less than 50 ml/24 hours. Perioperative antibiotics and bowel preparation were identical. Postoperative complications included pelvic abscess (n = 7), anastomotic leak/cuff sinus (n = 11), abdominal wound infection (n = 19), and perineal wound infection (n = 5). Postoperative irrigation of the pelvis did not result in a reduction in the overall rate of local pelvic septic complications. Positive intraoperative presacral cultures, the presence of anaerobes in the presacral space, and duration of pelvic drainage had no effect on the development of pelvic sepsis. 