Polyethylene glycol is the most commonly used intestinal cleanser in China. As a volumetric laxative, it cleanses the intestinal tract by evacuating large quantities of digestive juices without affecting intestinal absorption and secretion, and thus does not lead to disturbances in water and electrolyte balance. But for some special people’s intestinal preparation needs special attention. 1, pregnant and lactating women There is no literature to confirm that pregnant and lactating women for bowel preparation is harmful, so colonoscopy is relatively safe and feasible. There is no evidence to suggest that polyethylene glycol causes harm to the fetus, and polyethylene glycol has been shown to be safe for the treatment of constipation in pregnant women. Since a full colonoscopy is rarely necessary in pregnant women, saline enemas are recommended for sigmoidoscopy. When colonoscopy is necessary, breastfeeding can be done during bowel preparation and in the middle of the following days. 2. Children Bowel preparation in children should not only focus on the quality of the bowel preparation, but also on its tolerability. Electrolyte-free polyethylene glycol has been shown to be safe and effective as a bowel preparation drug in children and has become the most commonly used drug in bowel preparation in children. Sodium phosphate, on the other hand, is contraindicated in pediatric bowel preparation due to its high complication rate. Elderly patients have reduced colonic transport function and are often accompanied by multiple diseases and medications, all of which affect the quality of bowel preparation. Polyethylene glycol detergent rarely causes serum electrolyte disorders and blood volume changes in patients compared to sodium phosphate preparations, while cardiac, hepatic and renal functions are often impaired in elderly patients and tolerance to high dose laxatives is low, so low dose polyethylene glycol is the most ideal choice. 4, Diabetic patients The risk of acute renal failure may be higher when sodium phosphate is used for bowel preparation in diabetic patients, so it is recommended that polyethylene glycol should be preferred for bowel preparation in diabetic patients. Glucose-lowering drugs and insulin may be suspended during fasting, and enteroscopy should be performed in the morning if possible. If a hypoglycemic reaction occurs blood glucose levels can be raised by sugared sugar cubes or IV glucose solution.