The purpose of this study is to check if there is a difference in peritoneal contamination in patients undergoing rectal resection with closed and open rectal stump prior to anastomosing.

There is not much information regarding the peritoneal bacterial contamination during colorectal surgery. The null hypothesis is that there is no difference in peritoneal contamination following resection with closed or open rectal stump for left-sided cancer. Patients scheduled for elective resection are allocated for open resection with the distal stump closed or open. Anastomosis is performed while a clamp is placed on the rectal stump in one arm of the study while in the other arm, the stump remains open until the anastomosis is completed. A second bacterial sample will be obtained at the completion of the anastomosis from the same place (pelvic pouch) as the first one. After sampling an air leak test will be performed. A quantitative assessment of the number of Colony Forming Units (CFU/ml) of aerobic and anaerobic bacteria will be done for each patient. Operative time and time interval between samples will be measured. Postoperatively, possible complications (surgical site infections, leakage) will be monitored. The primary objective will be to determine the differences in peritoneal contamination between closed and open rectal stump during colorectal surgery.

Inclusion Criteria:

• Consecutive adult patients scheduled for a left colectomy, sigmoidectomy or rectal resection with a proposed anastomosis at the level of the rectum agreeing to participate in the study.

Exclusion Criteria:

• Patients without informed consent
• Class V patients on American Society of Anesthesiologists (ASA) of Physical Health Score
• Patient with prior peritonitis
• Patients with acute inflammatory bowel disease
• Recent antibiotic treatment