If you have eaten slightly before the colonoscopy, you can take laxatives such as mannitol injection or take an enema to clean the intestines, which is recommended to be done under doctor’s supervision. Enteroscopy is an examination method that inserts the enteroscope through the anus into the ileocecal region by following the lumen and observes the colonic lesions from the mucosal side, and it is necessary to clean the intestines before enteroscopy in order to see the lesions in the intestines clearly. Two days before the examination, patients should have a low residue, semi-liquid diet, such as eating thin rice, rice soup, etc., and avoid foods rich in high fiber as well as spicy and stimulating foods, while eating is not allowed on the day of the examination. If you accidentally eat something on the day of the examination, there will be food residue retained in the intestines, thus affecting the examination results. Such patients can take laxatives such as mannitol injection 4 to 6 hours in advance under the guidance of the doctor to help empty the intestines, and at the same time, they should drink plenty of water until the feces are completely cleared and clear water is discharged. Alternatively, enemas can be administered under medical supervision to cleanse the bowel. If you have eaten anything before the colonoscopy you should tell your doctor honestly so as not to affect the results.