Despite the name, yes, you do actually have to be there. The difference between a traditional and “virtual” colonoscopy (properly called CT colonography) is that the latter uses low-dose CT scanning (rather than an inserted colonoscope) to produce images of the colon and intestine. These images are used to screen for polyps in the large intestine, which have the potential to grow and become cancerous.
By examining the lower digestive tract with CT imaging instead of a traditional camera, the procedure becomes less invasive and safer for many patients, as there is no need for sedation, and the risk of perforating the colon is significantly reduced. An added benefit is that unlike traditional colonoscopy, CT colonography can sometimes detect dangerous conditions that need to be addressed outside the colon, such as early-stage cancers of nearby structures or abdominal aortic aneurysms.[1]
The day before the procedure, you’ll be asked to undergo a colon cleaning regimen, much like you would in preparation for a traditional colonoscopy. This allows the radiologist to more clearly see any polyps that might be present.
When you arrive for your exam, you’ll complete a medical history and change into a gown. The technologist will help you to position appropriately on your left side on the exam table and then pass a small, flexible tube just two inches into the rectum. Through this tube, carbon dioxide will flow into the colon, inflating it in order to obtain clearer images. You’ll be asked to roll onto your back and hold your breath briefly, and then do the same lying on your stomach while images are gathered. The whole procedure takes only about 15 minutes.
While patients commonly report a feeling of fullness after the procedure as a result of the gas that is pumped into the colon, fewer than 5% report significant pain.[2] The body naturally absorbs the gas in a short time following the exam.
Because a small chance of perforating the colon remains as the organ is inflated with carbon dioxide gas, be sure to let your health care provider know immediately if you do experience significant pain or fever, dizziness or weakness, or bloody stools following a CT colonography.
Currently, insurance providers are not required to cover CT colonography, but some are choosing to. It is, after all, less costly than a traditional colonoscopy. Check with your insurance provider to determine your level of coverage before scheduling your procedure.
During a traditional colonoscopy, biopsies can be taken as soon as abnormalities are identified. If you undergo CT colonography and polyps are detected, then you’ll have to schedule a traditional colonoscopy in order to have these biopsied. CT scanning always involves ionizing radiation, which contributes to an individual’s lifetime cancer risk. The radiation dose used in CT colonography, however, is roughly equivalent to what the average person receives naturally from the environment in the course of two years.[3] Finally, while traditional colonoscopy is recommended every ten years for most patients, virtual colonoscopy should be repeated every five years due to its decreased ability to detect smaller polyps.[4]
Iowa Radiology provides virtual colonoscopy at our downtown Des Moines location. Click the image below to access our free ebook for more information about CT scans, including CT colonography.
[1] "CT Colonography." Radiologyinfo.org. Radiological Society of North America, 19 Oct 2005. Web. 23 June 2017.
[2] Ibid.
[3] "Radiation Dose in X-Ray and CT Exams." Radiologyinfo.org. Radiological Society of North America, 8 Feb 2017. Web. 23 June 2017.
[4] "Virtual Colonoscopy: Frequently Asked Questions about CT Colonography." PDF. American College of Gastroenterology, 15 March 2009. Web. 23 June 2017.
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