There are usually two types of colonoscopy: colonoscopy and small bowel examination. 1. Colonoscopy: It is mainly to check the lesions in the colon and rectum. If there is pus and blood in the stool or symptoms such as diarrhea and constipation, the patient can undergo colonoscopy. 2. Small colonoscopy: It is mainly to check the lesions of duodenum, jejunum and ileum, if the lesions of colon and rectum are excluded, small colonoscopy can be performed. Generally, one day before the colonoscopy, you can choose liquid or semi-liquid food to promote food digestion and absorption; 6-8 hours before the examination, food and water should be prohibited so as not to affect the examination results. Enteroscopy can usually be used for the diagnosis and treatment of lesions. If patients experience discomfort, they should consult a doctor in time and under the guidance of a professional physician for the appropriate examination.