There is no consensus about the best bowel preparation prior to transanal endoscopic surgery TES). Cleanliness and visibility in the rectosigmoid and rectum are of utmost importance, possibly even more so than during colonoscopy, to facilitate safe, precise and efficient resection of the rectal lesion and potentially adequate closure of the defect. Both Fleet enemas and oral mechanical bowel preparation are considered standard of care in preparation for TES. This single center two arm single blinded randomized controlled trial will compare the effectiveness of Fleet enemas in comparison to Pico Salax oral mechanical bowel preparation in cleansing the rectum as measured by a modified version of the Ottawa Bowel Prep Scale.