Bowel Cleansing for Colonoscopy

The goal of this clinical trial is to learn which rescue bowel preparation works best for adults who need a repeat colonoscopy after a previous bowel preparation did not clean the bowel well enough. The study will also look at how satisfied participants are with each preparation. The main questions it aims to answer are: * Which bowel preparation helps more participants achieve adequate bowel cleansing before repeat colonoscopy? * Which bowel preparation leads to better cleansing in different parts of the colon? * Which bowel preparation is better tolerated by participants? Researchers will compare 3 rescue bowel preparation regimens to see which one works best for repeat colonoscopy after a previous cleansing failure. Participants will: * be randomly assigned to 1 of 3 bowel preparation regimens * take one of the following regimens before repeat colonoscopy: * 4 liters of polyethylene glycol (PEG) plus 12 milligrams of bisacodyl * 1 liter of PEG plus ascorbic acid plus 10 milligrams of bisacodyl * 2 liters of PEG plus extra PEG taken over the 3 days before colonoscopy * undergo repeat colonoscopy * rate their satisfaction with the bowel preparation

The purpose of this research is to compare patient preferences for two bowel preparation options: low-volume tablets (Suflave/Sutab) versus the standard colon preparation using Golytely (polyethylene glycol). The study aims to enroll approximately 300 patients, who will be randomly assigned to one of the two preparation methods in a 2:1 ratio prior to their scheduled colonoscopy appointments. Surveys will be conducted both before and after the procedures. This project will be conducted over a 12-month period and seeks to compare patient experience of both preparation methods in an outpatient setting. The study will evaluate the rate of preparation completion, patient satisfaction, tolerance of the solutions, and the endoscopic adequacy of each method. Eligible participants are patients aged 18 or older with upcoming colonoscopy appointments who can provide informed consent in English or Spanish. There is no health risks associated with this study, as both bowel preparation methods are FDA-approved and commonly used in clinical practice.