CT Colonography (CTC) is a specific CT examination to evaluate the colon and produce pictures similar to those obtained at colonoscopy. No telescope or sedation is required. It is essential that your bowel should be empty, and an accompanying leaflet will explain what you should eat and how you need to take the special laxative provided. This laxative is vigorous and to avoid inconvenience it is best to stay at home on the day before the examination. A small soft tube is inserted into the rectum, or back passage to allow carbon dioxide to be instilled into the bowel to distend it. You may be given an injection, generally of Buscopan, to relax the muscles of the bowel wall, and make the examination easier and helps reduce any cramp-like pain you may feel. A CT scan is then obtained with you lying supine (on your back) and then prone (on your front) to allow full evaluation of the colon. You may be given an intravenous injection of contrast. The advantage over a colonoscopy is that it can evaluate all the structures within the abdomen and pelvis not just the colon. CTC cannot obtain a sample of tissue if an abnormality is present as would be possible with a colonoscopy.