A colonoscopy is an examination of the inside of your large intestine, which includes your colon, rectum and anus. It's a type of endoscopy, which means that it uses an endoscope, a flexible tube with a lighted camera on the end that's inserted into your body. The procedure typically lasts between 20 to 45 minutes with another 30 minutes to an hour spent recovering from sedation. Colonoscopy is the most accurate method for diagnosing colon diseases (such as Colitis, Crohn's disease, or blockages), and is very important for diagnosing and preventing colon cancer by finding and removing polyps (pre-cancerous growths).