Specifically, colonoscopy is not recommended when any of the following are present: 1, severe cardiopulmonary insufficiency. 2. Severe hypertension, cerebral insufficiency, coronary arteriosclerosis, and obvious heart rhythm disturbances. 3, when peritonitis and toxic acute gastrointestinal inflammation (toxic bacillary dysentery, fulminant ulcerative colitis, acute gastroenteritis, etc.). 4, when acute gastrointestinal hemorrhage, blood accumulation in the intestine or excessive blood accumulation prevents observation. 5.When the gastrointestinal tract or pelvic cavity has recently undergone surgery and radiation therapy. 6.Surgery and inflammation resulting in intra-abdominal adhesions or the formation of hard distortions. 7.When there is narrowing of the anus and acute inflammation of the anus. 8.When there is stenosis in the intestine, the intestine above the stenosis cannot be forced into the mirror. 9.Patients with mental illness or those who cannot cooperate. 10.Women during pregnancy and menstruation.