Purpose/Background:​ Historically, mechanical bowel preparation (MBP) has been used
pre-operatively for colorectal surgery and was thought to cleanse the bowel and decrease the bacterial load within the colon. Multiple systematic reviews and meta-analyses have since proven that MBP is not superior to no preparation with regards to reduction of surgical site infections, anastomotic leaks, and post-operative sepsis for most elective colorectal procedures, and can be safely omitted from routine pre-operative care. Transanal endoscopic microsurgery (TEM) requires patients to receive pre-operative bowel preparation to allow for adequate visualization of the rectum. There is no current consensus within the TEM community on whether MBP or fleet enema represents the preferred bowel preparation regimen. The objective of this systematic review is to gather data from the literature to compare pre-operative MBP and fleet enema in terms of their impact on post-operative complication rates and quality of bowel preparation in TEM.

Methods/Interventions:​ The electronic databases of Embase, Cochrane Library, and Ovid
MEDLINE were systematically searched for TEM related studies. Only full length, English language
articles with n ≥ 100 were included. Each study was then assessed for author description of type of bowel preparation as well as documentation of post-operative outcomes. The primary endpoint was overall complication rates. Secondary endpoints were subgroup post-operative complication rates and surgeon satisfaction with bowel preparation.

Results/Outcome(s):​ Of the initially identified 752 studies, 21 were included in our analysis. A total
of 3567 patients from 16 studies were in the MBP group, and 819 patients from 5 studies were in the enema group. The overall post-operative complication rates were comparable between both groups (MBP – 13.9% vs fleet enema – 16.8%, p = 0.47). The most common post-operative complication was urinary retention, which was comparable between groups (MBP – 4.2% vs fleet enema – 6.1%, p = 0.59). Rates of infectious complications were also comparable (MPB – 2.0% vs fleet enema – 2.6%, p = 0.45), as were bleeding complications (MBP – 3.2% vs fleet enema – 2.12%, p = 0.42). There was no data on the quality of bowel preparation or surgeon satisfaction with preparation available.

Conclusions/Discussion:​ There is no evidence to suggest that MBP has any advantage over fleet
enema for pre-operative bowel preparation. However, there is currently no data from randomized
controlled trials directly comparing MBP and fleet enema. Our review suggests that clinical equipoise exists with regards to pre-operative bowel preparation in the TEM population but further studies are required. We plan to design a multi-center RCT to compare enema and MBP to assess for quality of preparation and post-operative complications with the hypothesis that fleet enema is non inferior to MBP in the context of TEM.

Bowel Preparation and Perioperative Complications in Transanal Endoscopic Microsurgery: A Systematic Review