A virtual colonoscopy (sometimes called a computed tomography colography) is a non-invasive procedure, meaning the screening is done completely outside the body. A virtual colonoscopy requires the same advance preparation as a standard colonoscopy.

During the virtual colonoscopy procedure, the physician inserts a small tube into the rectum to fill the colon with air. Then, instead of inserting a colonoscope into the rectum and through the colon like in a traditional colonoscopy, the physician uses MRI or CT scan technology to examine the colon from outside the body. The physician then carefully analyzes these images. If an abnormality is found, a traditional colonoscopy is required for further examination.