Colonoscopy is usually a procedure in which a thin tube with a light and lens for viewing is inserted through the rectum, into the colon. The physician, or medical specialist, then looks inside a person’s entire large intestine, or large bowel, from the lowest part, which is in the rectum, throughout the colon all the way to the small intestine. The main purpose is to find polyps or other early signs of cancer in the colon or rectum. Colonoscopy is also used to diagnose the reason for changes in bowel habits and other changes in the bowel like bleeding, inflammatin, or ulcers. The colonscope, or instrument used to look at the colon, may also have a tool on it to remove polyps, or take tissue samples (do a biopsy), which is afterwards examined under a microscope for any signs of cancer, usually colorectal or colon cancer.
There is a special kind of colonoscopy, called virtual colonoscopy, that is more costly than regular colonoscopy, and may not be covered by some health insurance companies. It is called Virtual Colonscopy, which is a non-invasive procedure in which no instrument is inserted in the rectum. Instead, images, or pictures, of the large intestine are taken using CT (computerized tomography) or CAT Scan or MRI (magnetic resonance imaging). Then, a computer puts the images together and creates a 3-D view of the inside of the large intestine.