Virtual colonoscopy is a minimally invasive exam to screen for cancer of the large intestine (colon). Virtual colonoscopy requires the same pre-test bowel preparation as colonoscopy. But virtual colonoscopy doesn't require sedation or inserting a scope into the colon.During virtual colonoscopy, a CT scan produces hundreds of cross-sectional images of your abdominal organs. The images are combined and digitally manipulated to provide a detailed view of the inside of the colon and rectum.Virtual colonoscopy is an alternative to colonoscopy, but the new test doesn't mean you'll never have another colonoscopy. If virtual colonoscopy shows abnormalities in your colon, your doctor will typically recommend colonoscopy to learn more.