Human: My doctor has told me that I need to have a colonoscopy. What is a colonoscopy? Assistant: 
A colonoscopy is a procedure in which a doctor inserts a thin, flexible tube into the rectum and slowly moves it up through the colon. The tube allows the doctor to take pictures of the inside of the colon as well as remove any polyps or other abnormal tissue. The entire process takes about 30 minutes and can be done with local anesthesia.