Small bowel cleansing is generally referred to as bowel cleansing and is a required preparation prior to some bowel surgeries or colonoscopies. Generally, 2 days before the bowel cleansing is performed, you need to eat easy-to-digest foods, preferably fluids, to combat constipation. 1 night before the bowel cleansing, oral intestinal cleanser prescribed by the doctor, while drinking plenty of water, no longer eat, the specific amount of water, as much as possible within the tolerance of the discharge of clear liquid is appropriate. Your doctor will usually recommend taking both a bowel cleanser and an antifoam to empty the digestive juices, cleanse the bowel, and try to avoid disturbances in the water and electrolyte balance. On the day of bowel cleansing, you should abstain from food, water and medication in the morning. Before performing a colonoscopy or surgery in the morning, you can ask your doctor if it would be appropriate to drink some colorless sugary drinks to avoid hypoglycemia. If the procedure or colonoscopy is performed in the afternoon, you should receive the relevant medication a day in advance and take the bowel cleanser and antifoam at least 6 hours before the procedure or examination on the same day, so as to allow sufficient time for bowel cleansing.