Having slag in the bowel proves that the bowel is not clean, which may affect the examination results, and it is not possible to do colonoscopy. However, if the patient has an underlying disease, can not be completely clean bowel, or incomplete intestinal obstruction and other pathological conditions, a little bit of slag in the stool can still be examined, but it may affect the examination results, resulting in missed diagnosis. The most important role of colonoscopy is for the examination of intestinal diseases and colorectal mucosal lesions, which is an intestinal examination with higher requirements for intestinal cleanliness, and has the advantages of early detection, early discovery and early treatment. Because there are many folds in the colon, if there is some fecal sludge in the intestines, some lesions may not be easily detected or even missed. Therefore, when doing colonoscopy, the doctor will ask the patient to clean the intestines, and more often use enema and take laxatives to expel the feces out of the body for many times, until the discharge of water, which means that the patient’s intestinal cleansing is completed, and intestinal examination can be carried out. Whether or not a colonoscopy can be done still needs to be determined by the doctor according to the actual situation. After the end of the intestinal examination, do not perform strenuous exercise for three days, eat more light-flavored food, and if abdominal pain occurs, consult a doctor promptly.