This is a pilot randomized-controlled trial assessing the utility of ondansetron for improving pediatric pre-colonoscopy bowel prep outcomes using the boston bowel preparation score, as well as assessing the impact on patient experience of bowel preparation.

The study will compare two approaches to pre-colonoscopy cleanout, one with traditional laxatives only, and one with laxatives + anti-emetic therapy. The medication to be added will be Ondansetron (brand name: Zofran). Classically, the bowel prep entails drinking large amounts of water with an osmotic laxative and being only on a liquid diet the day prior to the procedure. Drinking this mixture of water with an osmotic laxative may cause nausea and discomfort in some patients that may prevent them from finishing the bowel prep. This will therefore affect the visualization of the colon during the procedure, as there will still be retained, hard stool. Having large amounts of stool in the colon during the procedure can make the colonoscopy more difficult, takes a longer time to complete, can make the study inconclusive, unable to properly diagnose, and difficult to take biopsies. This study assesses the impact of anti-emetic medication (ondansetron) on the bowel prep experience with the goal of improving participant tolerance and preparation success. This will eliminate concern for retained stool and less chance of cancelling a procedure due to improper bowel prep.

Inclusion Criteria:

• Age >2, <20
• clinically indicated for a colonoscopy

Exclusion Criteria:

• known arrhythmia or long QT