Virtual colonoscopy, also known as CT colonography, involves using a CT scanner to produce two and three dimensional images of the large bowel and rectum.
This can be used for patients who are not suitable for regular colonoscopy due to other medical reasons. If you had a conventional colonoscopy and the doctor could not see your entire bowel, he/she may recommend that you have a virtual colonoscopy.
Before the procedure, the specialist nurse will talk to you about the bowel preparation that you will have to take to make sure that the bowel is empty. This ensures that the images are as clear as possible. The nurse will ask you about any medical conditions (e.g. diabetes, kidney problems) that they need to be aware of prior to you taking the bowel preparation.
During the procedure, gas is used to inflate the bowel via a thin flexible tube placed in your back passage. CT scans are then performed with you lying on your back, and then on your front, to enable the doctors to get a clear set of scans of your bowel. You will be asked toh old your breath for approximately 20 seconds in both positions.
The disadvantage is that if anything abnormal is detected, you may need a regular colonoscopy at a later date to allow the doctor to remove polyps and take samples (biopsies).
Virtual colonoscopies are not currently available in every hospital.