What you can expect

By Mayo Clinic Staff

During the exam

During a virtual colonoscopy, you'll wear a gown but likely no other clothes. Sedation isn't usually necessary, but you may be given an injection of medication to reduce the likelihood of stomach cramps during the exam.

You'll begin the exam lying on your side on the exam table, usually with your knees drawn toward your chest. The doctor will place a small tube (catheter) inside your rectum to fill your colon with air or carbon dioxide. The air or gas — which helps create clear images — may cause a feeling of pressure in your abdomen.

For the next part of the exam, you'll lie on your back. The exam table will be moved into the CT machine, and your body will be scanned. Then you'll turn over to lie on your abdomen or your side, and your body will be scanned again. You may be asked to turn and hold various other positions, as well as hold your breath at times. If necessary, a contrast agent may be given through a vein in your arm (intravenously) to help create clearer images.

A virtual colonoscopy typically takes about 10 minutes.

After the exam

After the exam, most of the air or gas will be removed from your colon through the catheter in your rectum. You may feel bloated or pass gas for a few hours after the exam as you clear the remaining air or gas from your colon. Walking may help relieve any discomfort, and you can return to your usual diet and activities right away. Consult your doctor if your signs and symptoms don't improve on their own.

Jun. 18, 2011