What is a virtual colonoscopy?
A virtual colonoscopy, also known as CT colonography, is a type of scan that produces detailed images of the large bowel using low bursts of radiation. This scan is generally used to look at small growths called polyps in the colon and to detect intestinal cancer.
What does it involve?
A virtual colonoscopy is similar to other types of CT scans. It involves lying on a bed inside a CT scanner that rotates around you taking hundreds of detailed images of your abdominal organs. These are combined to produce a three-dimensional model of your large intestine and any growths within it. The physician can then “look inside” the model, as if you were actually traveling through the colon.
Unlike a traditional colonoscopy, a virtual colonoscopy can be performed while you are awake, and is much faster, about 15 minutes to complete.
A virtual colonoscopy is a type of scan that produces detailed images of the large intestine using low
detailed images of the large intestine using low bursts of radiation.
Why is it performed?
A colonoscopy is commonly performed to detect small growths called polyps in the large intestine. These do not cause symptoms, but can develop into bowel cancer if not removed, so it is important to detect them early.
A colonoscopy is recommended only as a follow-up of polyps found during the bowel camera examination. In most cases, a traditional colonoscopy is offered, but some people who have health problems may make this unsafe. In this situation, a virtual colonoscopy is an effective alternative.
How to prepare
Your doctor will advise you on some dietary restrictions before the test. You may be asked to clean out your bowels, in which case you may only be able to drink fluids the day before the test and you may be given medication or a laxative. It is usually necessary to drink a contrast fluid to help the polyps show up better on the scan. You should inform your doctor if you have heart, liver or kidney problems, as this process is not safe for everyone.
You should also inform your doctor if you might be pregnant.
What to expect
The procedure is very quick and painless. You will be asked to lie on the test table and a small tube will be inserted into your rectum to help inflate the bowel and reveal any “hidden” polyps.
The test table will slide into the scanner, which will rotate around you capturing images at high speed. You may be asked to hold different positions, turn backwards or sideways, or hold your breath for a few seconds. Once the scan is complete, the tube will be removed and you will be free to leave.
What do abnormal results mean?
In the vast majority of cases, an abnormal result means that polyps have been found, but they are not cancerous. If polyps are found, they cannot be removed during a virtual colonoscopy, so you will need to come back for another appointment.
Bowel cancer is a much rarer outcome. If it is found, you will likely be given an appointment to see a specialist as soon as possible.
Advances/progress.
Virtual colonoscopies have benefited from recent advances in CT scanning technology. Now, CT scanning machines can produce much more detailed images, creating an accurate three-dimensional model that is effective in recognizing larger polyps. The speed of picture-taking has also increased, which means less time on the test table and a better patient experience.