It is recommended to go for a colonoscopy when the body experiences unexplained bloating, weight loss, change in bowel habits, etc., or when there is a family history of related diseases. Gastrointestinal symptoms such as diarrhea, bloating, abdominal pain, fatigue, weight loss, and anemia may occur with some intestinal diseases, such as ulcerative colitis. If unexplained symptoms of the above are present, a colonoscopy is recommended at this time. If there is a change in bowel habit and nature, such as excessive defecation, constipation or alternating diarrhea and constipation, with no improvement after diet and medication, or symptoms such as black stools, bloody stools, mucus-like stools, etc., colonoscopy is needed. If the immediate family or close relatives of people over 50 years old suffer from digestive system tumors, such as stomach cancer, intestinal cancer and other diseases, colonoscopy is recommended. Colonoscopy is a commonly used examination method in gastroenterology, which can visualize whether there is congestion, polyps, tumors, etc. in the colon and rectum, and at the same time, lesions found can be pathologically examined, so as to accurately diagnose some of the intestinal diseases.