Colonoscopy is the most direct and effective method of examining intestinal disorders and includes both colonoscopy and small colonoscopy, of which colonoscopy is more commonly used. Colonoscopy is primarily used to assist in the diagnosis of diseases present in a patient’s intestinal tract as well as to treat them accordingly. Colonoscopy mainly examines the large intestine, entering through the anus and traveling upwards and retrograde, passing through the rectum, sigmoid colon, descending colon, transverse colon, ascending colon, cecum, and the end of the ileum. Small colonoscopy mainly uses capsule endoscopy and double airbag small colonoscopy. The double balloon small colonoscopy is usually divided into two types of upper and lower transthoracoscopy, which is usually performed under general anesthesia of the patient. The upper transthoracoscopy is performed from the oral cavity to the jejunum and ileum, and the lower transthoracoscopy is performed from the rectum to the cecum, and then to the ileum and jejunum. The upper and lower transthoracoscopes are then intersected to view the small intestine for polyps, tumors, diverticula and other lesions. Patients who experience discomfort should undergo colonoscopy under the guidance of a medical professional.