To do a colonoscopy, bowel preparation is very important, some patients have to re-prepare and re-examine due to poor bowel preparation, because even the best doctors are difficult to determine the bowel hidden under the fecal water, the international recommendations: first time colonoscopy patients, if the bowel preparation is inadequate, it is recommended that the colonoscopy should be re-examined again within 1 year. Therefore, a standardized bowel preparation is necessary to make your bowel examination a success and avoid repeat examinations due to poor bowel preparation. Dietary Requirements Before Bowel Preparation Avoid red or seedy foods such as watermelon, tomatoes and kiwi for 1-2 days prior to the examination. Eat less crumbly semi-liquid food such as thin rice and noodles for lunch and dinner on the day before the examination, no food with more crumbs such as vegetables, fruits and dairy products. Polyethylene glycol preparations 1, polyethylene glycol preparations: our guidelines recommend to be patients with polyethylene glycol preparations bowel preparation is recommended to patients to drink 2-3L of water, certain short time can not drink a lot of water patients are recommended to be 1 day before colonoscopy diet control. Polyethylene glycol preparations for volumetric laxatives, through a large number of emptying digestive juices to clean the intestinal tract, will not affect the intestinal absorption and secretion, will not lead to disorders of water and electrolyte balance, the common adverse reactions are abdominal distension, nausea. 2, magnesium sulfate: its characteristics are faster acting, the effect is too strong, 50% concentration of magnesium sulfate need to be diluted in half with water and then drink, the disadvantage is that it is easy to lead to dehydration and electrolyte disorders, must be taken at the same time in order to replenish the water and electrolytes, not as a routine program. How to take laxatives We take “Polyethylene Glycol Electrolyte Bulk” as an example to introduce the bowel preparation method. Patients who are not constipated usually start taking the laxative 4-6 hours before the test. Pour all of the polyethylene glycol electrolyte powder into a large container, add warm water to 2,000-3,000 ml to fully dissolve it, and finish it within 2 hours. Usually, the laxative is taken for about half an hour, and then “diarrhea” occurs, usually 7-10 times, until there is no visible solid fecal sludge. The “diarrhea” usually occurs after half an hour of taking the laxative, usually around 7-10 times, until no solid fecal sludge is visible. The standard for bowel cleansing is “colorless watery stools with no solid feces”. Precautions before the test 1. If you are constipated for a long time, please explain to your doctor. A small amount of laxative can be taken 3 days before the test. 2. If you routinely take antihypertensive medication, you can take it 1 hour before taking the laxative. Diabetic patients do not need to take glucose-lowering medication because they are not eating. 3.Non-diabetic patients can drink some white sugar water appropriately if they have hypoglycemic manifestations. 4, if you need enteroscopy for electrocision and other treatments, and you are also taking aspirin, clopidogrel, warfarin and other anticoagulants, be sure to explain to the doctor. 5, after the examination, do not eat immediately, if not carried out polypectomy, to be discharged in the colon gas, bloating disappears into the easily digestible liquid food, if the polypectomy, need to continue to receive treatment under the guidance of the doctor.