What is a Non-Invasive Colonoscopy?

A non-invasive colonoscopy is one during which a doctor obtains images of a patient’s large intestine and uses a computer to turn those images into a three-dimensional, animated view of that intestine. Often referred to as a virtual colonoscopy, this procedure can be performed using either computerized tomography (CT) or magnetic resonance imaging (MRI). The purpose of a virtual colonoscopy is the same as that of a regular colonoscopy, which is to search for polyps, colon cancer, and other irregularities or diseases. Preparing for and undergoing a virtual colonoscopy is similar to preparing for and undergoing a traditional colonoscopy. As is the case with most medical tests, a virtual colonoscopy presents both advantages and disadvantages.

The bowel prep for a non-invasive colonoscopy is similar to that of a traditional colonoscopy. For one to three days before the procedure, the patient needs to clean his gastrointestinal tract of all solids. During the time period, the patient consumes a liquid diet that can consist of water, plain coffee and tea, and broth, though some doctors allow solid foods like gelatin.

The night before the virtual colonoscopy is scheduled, the patient takes a laxative. Typically, the laxative is a pill or a powder the patient must mix and drink with water. Sometimes, the patient’s doctor recommends also using a suppository to remove any fecal matter the laxative left behind. Even so, it’s sometimes necessary for the patient to undergo what’s known as fecal tagging. During this process, the patient drinks a substance designed to coat any remaining fecal matter so the doctor can identify it and exclude it from the results.

Usually, the patient drinks a medical contrast medium once it’s time to perform the non-invasive colonoscopy. This medium is a liquid designed to help the doctor locate abnormalities by making the large intestine appear bright. The doctor then explains how the patient should position himself on the table, but patients lie on their stomachs, backs, sides, or some combination of the three in most cases.

Next, the doctor inserts a thin tube into the patient’s rectum through his anus. If the procedure involves a CT, the tube pumps carbon monoxide into the large intestine to expand it. For an MRI, however, another contrast medium is used to expand the large intestine. In order to make sure the images are steady, the patient might need to hold his breath at certain times during the procedure. Overall, a virtual colonoscopy can take up to 15 minutes.

There are both advantages and disadvantages to a non-invasive colonoscopy. For example, a non-invasive colon test can provide clearer images, doesn’t involve the entire length of the colon, and typically doesn’t require sedation. On the other hand, these tests still require tube insertion, don’t allow for the removal of polyps, and can’t detect certain smaller polyps. Some health insurance plans don’t cover virtual colonoscopies, and until the technology becomes more widely known, not all medical practices have the equipment to perform them. Based on these pros and cons, each patient and his doctor will determine whether a virtual colonoscopy is right for him.