A Virtual Colonoscopy (CT Colonography) is a minimally invasive screening method that uses a CT scanner to create two and three-dimensional images of the colon and rectum. This non-invasive procedure serves as an alternative to traditional optical colonoscopy for detecting polyps and signs of colorectal cancer. The scan utilizes specialized X-ray technology and computer software to provide a detailed internal view of the large bowel.
Identifying Facilities and Specialists
A Virtual Colonoscopy is performed in facilities equipped with a modern Computed Tomography (CT) scanner and the specialized software required to process the images. These procedures are commonly offered at the radiology departments of large hospital systems and academic medical centers. Specialized outpatient radiology or imaging centers also frequently provide this service.
The interpretation of the scan is done by a radiologist, who is a physician specializing in medical imaging. These radiologists must have specific training in reading CT Colonography images to accurately identify polyps or other abnormalities. To find a location, check your health insurance provider’s directory for in-network radiology groups or imaging centers. Contacting the radiology department directly at a local hospital can confirm their capability and the necessary physician referral process.
Scheduling, Referrals, and Preparation
Obtaining a Virtual Colonoscopy begins with securing a physician’s order or referral, usually from a primary care physician or a gastroenterologist. This referral is a prerequisite for scheduling the appointment and ensures the procedure is medically appropriate. Once the referral is in place, coordinate the appointment through the facility’s radiology scheduling department.
Bowel Preparation
The most involved part of the process is the required bowel preparation, which is similar to the preparation for a traditional colonoscopy. A thoroughly cleansed colon is necessary for the radiologist to clearly visualize the inner lining and accurately detect polyps. Preparation begins a day or more before the scan and involves following a strict clear liquid diet and taking prescribed laxatives.
You will also be instructed to drink a liquid contrast agent, such as Gastrografin, which coats any remaining stool in the colon. This tagging process allows the computer software to differentiate between residual material and polyps on the final scan images. Adhering strictly to these instructions is necessary; inadequate cleansing can obscure the results and may require the procedure to be rescheduled.
What to Expect During the Scan
When you arrive for the exam, you will change into a gown and be taken to the CT scanning room. The actual time spent in the scanner room is relatively short, usually lasting only about 15 to 20 minutes. You will lie on your back on the CT table, and a technologist will gently insert a small, flexible tube into the rectum.
Through this tube, carbon dioxide gas or air is slowly introduced to inflate the colon (insufflation). This expansion flattens the colon walls so the CT scanner can capture clear images of the entire inner surface. You may feel bloating or fullness, but carbon dioxide is preferred as it is absorbed faster than air, potentially reducing post-procedure discomfort.
The technologist will take two sets of images: one while you are lying on your back (supine) and a second while lying on your stomach (prone). This change in position allows gravity to shift any fluid or residual matter, ensuring the entire surface of the colon is visualized from different angles. You will be asked to hold your breath for a few seconds during each scan to minimize motion. Because no sedation is used, you can immediately resume your normal activities, including driving, after the procedure.
Cost and Follow-Up Procedures
Insurance coverage for Virtual Colonoscopy is variable and often depends on whether the procedure is classified as a screening or a diagnostic test. Some private insurance plans may cover the cost for routine screening, but coverage is not universal. Medicare, for instance, covers the test only if a traditional optical colonoscopy was incomplete or medically contraindicated, classifying it as diagnostic. Contact your insurance provider beforehand to understand your specific benefits and potential out-of-pocket costs.
Once the radiologist interprets the images, the results are sent to your referring physician. If the scan reveals no abnormalities, you will continue with your recommended screening schedule. However, if the Virtual Colonoscopy detects a significant polyp or mass, a follow-up action is required. Because the Virtual Colonoscopy is a diagnostic imaging test and not therapeutic, any suspicious findings necessitate a subsequent traditional (optical) colonoscopy. This procedure allows a gastroenterologist to visually inspect the area, perform a biopsy, and remove the polyp.