A virtual colonoscopy may be ordered for several reasons. It is most frequently used to diagnose colorectal cancer and polyps. However, it is not recommended as a screening tool for colorectal cancer by American Cancer Society. A virtual colonoscopy can also be used to identify digestive or inflammatory diseases including diverticulosis and other tumors. It is helpful for determining the cause of bleeding. Additionally, a virtual colonoscopy may be used as a follow-up assessment after a colonoscopy.
A virtual colonoscopy is an outpatient procedure that is performed in the radiology department of a hospital or medical center. The procedure does not require sedation or anesthesia. Preparation instructions for a virtual colonoscopy generally consist of methods to empty or clean your bowel prior to the test including the use of laxatives, enemas, or a liquid diet. Your doctor will provide you with specific instructions. You will need to remove all jewelry, dentures, metal hair clips, body piercing jewelry, and other metal items that might show up on a scan before your procedure.
You will wear an examination gown for the procedure. To begin, you will lie on your left side on an examination table. A thin flexible tube will be gently placed through your anus and into your rectum. Air will be administered through the tube to inflate your colon. Making the colon bigger provides a better view and allows a more thorough examination. After the air is inserted, you will lie on your back.
The table will move through the opening of a scanning machine that will take images of your colon. The procedure may use magnetic resonance imaging (MRI) or computed tomography (CT) scans. You will be asked to remain still and hold your breath at times while the images are taken. You may be asked to change positions to provide pictures from different angles. The images are sent to a computer that compiles them into a three-dimensional (3D) picture of your colon. When the procedure is completed, the thin tube is carefully withdrawn.
The procedure may cause temporary discomfort from the air that is pumped into the colon. You may feel temporary abdominal cramping or gas pain. MRI and CT scanning are painless procedures. They simply require that you remain motionless while the pictures are taken. You may return to work or your normal activities after the procedure. Your doctor will instruct you on how to increase your food and liquid intake.
A radiologist will evaluate the images from your virtual colonoscopy. If abnormal results were found by your test, your doctor will discuss next step planning with you. If a polyp is found on a virtual colonoscopy, it needs to be examined and possibly removed with a colonoscopy.