Colonoscopy is a procedure in which a thin, soft endoscopic tube with a lens is inserted into the patient’s intestinal cavity from the anus, and with the help of the lens, specific lesions in the rectum, the sigmoid colon, the descending colon, the transverse colon, the ascending colon, the cecum, and other large intestinal cavities are clearly observed, and suspected intestinal tissues can be taken off and pathologically examined when the lesions are detected. Therefore, colonoscopy is known as the gold standard for colorectal cancer diagnosis. During colonoscopy, in order to make the endoscope enter into the intestinal cavity smoothly, the medical staff will inflate the patient’s intestines from time to time; at the same time, it can get a better and clearer view of the intestinal tract to facilitate better observation of the intestinal lumen; during the initial inflation process, the patient will feel a sense of abdominal distension, but following the instructions of the medical staff, the feeling of abdominal distension will be gradually adapted. In addition, because the human intestinal tract is “curved”, when the mirror reaches the corner bends, the pain will be accompanied by a feeling of abdominal distension (each person’s intestinal tract is different, so the pain is different from person to person, and it is not true that all people have a similar feeling). Colonoscopy is aimed at the large intestine of the human body, the bloating and pain produced during the examination process can be tolerated by the general public, except for a few patients with poor tolerance, the general patients can choose the general colonoscopy examination. The small intestine is usually examined by small colonoscopy, small colonoscopy can be entered from the mouth or anus, and the examination means is similar to colonoscopy; however, since the length of small intestine accounts for four-fifths of the whole intestine, it is necessary to hover several times in the abdominal cavity during small colonoscopy, which brings pain that is difficult to tolerate, therefore, the examination of the small intestine can be chosen to be carried out by painless small colonoscopy or capsule endoscopy.