Information for patients>CT Colonography (Virtual Colonoscopy)CT Colonography (Virtual Colonoscopy)
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Frequently Asked Questions - CT Colonography (Virtual Colonoscopy)What are the common uses of CT Colonography? Who should be screened using CT Colonography? How should I prepare for this procedure? How is the procedure performed? What will I experience during the procedure? What is CT Colonography? CT imaging uses special x-ray equipment to produce multiple images of the the body that can then be examined on a computer. CT scans of internal organs, bones, soft tissue and blood vessels provide greater clarity than conventional x-rays. CT colonography uses CT scanning to obtain a 3D view of the inside of the colon. What are the common uses of CT Colonography? The main reasons for performing CT Colonography are to detect colon cancer and to screen for polyps. Although polyps are generally benign growths, they can grow and turn into cancers. If these growths are found in their early stages they can be removed before cancer has had a chance to develop. Who should be screened using CT Colonography? Many doctors agree that everyone older than 50 years of age should be screened for polyps every 7 to 10 years. Individuals at increased risk, (i.e a history of polyps, family history of bowel cancer or the presence of blood in the stool) should be screened every five years. How should I prepare for this procedure? It is important that you clean out your bowel the night before your CT colonography examination, so that the radiologist can see any polyps that might be present. Accordingly, you will be given written instructions on what you can eat or drink before your examination, and you will also be required to take laxatives. Your doctor needs to be aware if you have heart, liver or kidney disease, or if you take tablets for diabetes, as this may affect the preparations for the scan and your medical regime immediately afterwards. Women should also notify their doctor and the radiologist if there is any possibility that they are pregnant. How is the procedure performed? The radiologist will explain the test and answer any questions. The procedure will take between 15 and 20 minutes. You may have a cannula inserted into one of the veins in your arm. The radiographer will position you on the CT scanner table. A small injection of muscle relaxant into the cannula prevents the bowel from going into spasm. A small, flexible tube will be passed two inches into your back passage to allow air or carbon dioxide gas to be gently pumped into your bowel, inflating it to distend the bowel to allow tumours and polps to be seen. What will I experience during the procedure? Most patients report a feeling of bloating and mild discomfort when the bowel is inflated, as if they need to break wind, but it is very unusual for the procedure to be painful. After the tube is inserted, your privacy will be respected. The actual scanning procedure itself is completely painless, although you will be aware of the CT scanner's slight buzzing, clicking and whirring as it revolves about you during the imaging process. You will be alone in the examination room during the actual scan, but the radiographer will be able to see, hear and speak with you at all times. Are there any risks? CT colonography is generally regarded as a very safe test. Problems can occur rarely and, if they do, they are similar to those which could happen with other methods of examining the large bowel.
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