You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is The commonest site of perforation during colonoscopy is - and explain in detail?
• Risks of colonoscopy: Perforation and hemorrhage
• MC site of bleeding after colonoscopy: Stalk after polypectomy.
• MC site of perforation during colonoscopy: Sigmoid colon
• Perforation can be caused by excessive air pressure, tearing of the antimesenteric border of the colon from excessive pressure on colonic loops, and at the sites of electrosurgical applications