Colonic transit: what is the impact of a diverting loop ileostomy?

Background: Diverting loop ileostomy (DLI) is used following low anterior resections (LAR) or ultra-low anterior resections (ULAR) to reduce anastomotic leak (AL). Preoperative mechanical bowel preparation (MBP) is traditionally used with DLI. However, clearance of the left colon can be achieved with a fleet enema without the physiological compromise of MBP. We aimed to assess colonic transit following DLI in this context. Methods: Aprospective, observational study was performed with patients with rectal cancer undergoing LAR or ULAR in a tertiary colorectal unit with preoperative fleet enema. Radiopaque markers were inserted into the caecum following rectal resection and formation of a DLI with placement confirmed by image intensifier and endoscopy. X-rays were performed at days 1, 3, 5 and 14 post-operation with data collected prospectively. Results: Ten patients (mean age 57, nine males) were enrolled. Mean time to functioning stoma was 1.9 days (range 1-3). There was no movement in the majority of markers in all patients at Day 5 post-operation. In all seven patients with Day 14 X-rays, the majority of markers remained in the right colon. Two patients had delayed AL, with markers found within the pelvis in both of these patients. Conclusions: This is the first study to assess colonic transit following DLI using fleet enema only, with results suggesting colonic motility is abolished in this setting. The use of a fleet enema without MBP may be sufficient prior to rectal resection surgery when DLI is employed. AL may actually increase colonic transit. Further research is warranted.