What you can expect

During the exam

You'll wear a gown, but likely no other clothes. Sedation usually isn't necessary, but you may be given medication to relax your colon.

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 helps create clear images and 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.

A virtual colonoscopy typically takes about 10 to 15 minutes.

After the exam

You can resume your usual activities after your virtual colonoscopy. You may feel bloated or pass gas for a few hours after the exam as you clear any remaining air or gas from your colon.