It is better to discharge clear water before colonoscopy, which is a symbol of cleaning the intestines in place, and is conducive to seeing the intestinal mucosa and so on more clearly during colonoscopy. Before the colonoscopy examination, you need to clean the intestines and expel the feces in the body, including the parts that are easy to remain such as the wrinkled wall of the intestines, usually by drinking some laxatives, such as compound polyethylene glycol electrolyte dispersions, etc., to promote the excretion of feces in the intestines, and it is preferable to excrete clear water to avoid feces interfering with the examination of colonoscopy. If you go for colonoscopy without waiting to expel clear water after cleaning the intestine, then there is a possibility that fecal sludge will remain in the intestine, which may paste on the lens of colonoscopy, affecting the field of vision and should be examined. That is why it is important to expel clear water to comply with the colonoscopy.