A virtual colonoscopy is a procedure that uses X-rays or magnetic resonance imaging to create images of the colon and the rectum, according to the National Institute of Diabetes and Digestive and Kidney Diseases. A virtual colonoscopy can reveal polyps, ulcers and swollen tissue.
The test is performed by the insertion of a small tube through the anus and into the rectum while the patient lies on a table. To get a better image, the large intestine is inflated by the tube. Pumping air into the colon can cause gas pains, states MedlinePlus. The radiologist takes the X-ray images by sliding the table into a CT or MRI machine. The computer synthesizes the images to create three-dimensional pictures of the colon. A virtual colonoscopy generally lasts about 10 to 15 minutes.
This procedure can be used to screen for colon cancer, notes WebMD. Also called computed tomographic colonography, a virtual colonoscopy is done to monitor polyp growth; diagnose changes in bowel habits, abdominal pain and weight loss; and to evaluate abnormal results from other tests. Normal findings indicate a healthy intestinal tract, but abnormal findings may suggest inflammatory bowel disease, tumors, diverticulosis or colorectal cancer. Risk includes exposure to radiation. The chance of bowel perforation during a virtual colonoscopy is minimal compared to that of a regular colonoscopy, according to MedlinePlus.