Intraoperative Testing of Colorectal Anastomosis - Air or Water (Methylene Blue)?

A leak from a colorectal anastomosis is a post-operative complication surgeons fear the most, following colonic resection. Over the years, there have been multiple suggestions for intraoperative tests for the integrity of the colorectal anastomosis. Two of the most common tests that are performed routinely are: 1. Air tight leak test - filling the pelvis with saline and insufflating air trans anal - looking for air bubbles in the saline filled pelvis. 2. Injecting diluted dye (methylene blue) trans anal, and looking for blue dye stains on gauze pads covering the outer side of anastomosis. The aim of the study is to compare the two methods, and to assess if there is a superior method. A secondary aim is to establish standards to perform the test, mainly to assess the appropriate pressure to apply on the anastomosis. In this prospective study patients scheduled to undergo colonic resection of their distal part of the colon/ rectum with colorectal anastomosis, will have both testing methods performed sequentially and will be followed post-operative to assess the yield and sensitivity of the testing methods.