human
I've been told that I need to have a colonoscopy. What is it and why is it necessary?
assistant
A colonoscopy is a procedure in which the doctor inserts a long, flexible tube into your rectum and then uses a lighted camera to examine the lining of your large intestine. It is used to diagnose and treat various conditions, including polyps, colitis, cancer, and Crohn's disease. The procedure can also be used to screen for colorectal cancer.