Virtual Colonoscopy for Colorectal Cancer Screening
Virtual colonoscopy is a procedure that is done to look for small polyps or other
growths inside your colon. Polyps that grow on the inside lining of the colon may
turn into colon cancer. The American Cancer Society advises that most men and women
at average risk start screening for colon cancer at age 45. If you have a family history
of colon cancer or are at high risk for other reasons, you may need to have screening
even earlier. Virtual colonoscopy every 5 years is one of several screening choices.
Virtual colonoscopy is also called CT colonography. CT stands for computed tomography.
A CT scanner takes many X-rays of the colon that are processed by a computer. The
computer puts all the X-rays together to create 3-D images of your colon and rectum.
Reasons for the procedure
Colon cancer is a common cancer in men and women. The reason for virtual colonoscopy
is to find colon cancer at an early stage when it can be treated more easily. Regular
colonoscopy is also used to screen for colon cancer. A long, flexible, lighted scope
and tiny camera a put into the rectum and up into the colon. This lets the healthcare
provider look at the colon directly and remove any polyps that are there. Colon polyps
that are found by virtual colonoscopy can be removed with regular colonoscopy before
they turn into cancer.
Virtual colonoscopy has some benefits over regular colonoscopy:
It's less uncomfortable and invasive. It usually doesn't need to include any pain
medicine or anesthesia.
It takes less time.
It poses less risk of harming the large intestine.
It may be used for some people who are not be able to have regular colonoscopy. In
certain cases, it may be used in people who have problems such as swelling, bleeding,
or breathing problems.
It may be able to show areas of the large intestine that regular colonoscopy can't
reach. This may be the case if part of the intestine is narrowed or blocked.
Risks of the procedure
Every procedure has some risks and possible problems. For virtual colonoscopy, these
A small, short tube is placed into your anus so that air can be pumped into your colon.
This inflates your colon so that polyps or other growths are more easily seen. Pumping
air into the colon carries a very small risk that it may cause a tear (rupture). But
the risk is thought to be less than with regular colonoscopy.
Polyps or other growths can't be removed or biopsied with a virtual colonoscopy. You
will still need to have a regular colonoscopy if polyps or other growths are found.
The procedure can miss some polyps if they are smaller than 10 mm. Some of these might
be seen by regular colonoscopy.
Unlike most other screening tests, the test uses X-rays to create pictures of the
colon and rectum. The amount of radiation is small. But it may still raise your risk
of cancer slightly. It could also be dangerous for pregnant women. If you are or could
be pregnant, talk with your healthcare provider before the procedure.
Virtual colonoscopy may not be covered by health insurance.
You may have other risks, depending on your health. Be sure to discuss any concerns
with your healthcare provider before the procedure.
Before the procedure
Tell your healthcare provider about any medicines you are taking. Before having a
colonoscopy, you will need to have a bowel prep. A bowel prep helps you empty your
colon so that the CT images will be clear. Here is how bowel prep is often done:
Your healthcare provider may ask you to limit your diet to clear liquids for 1 or
2 days before the procedure. These might be water, clear broth, or an electrolyte
The day before the procedure, you will be given a strong laxative in pill or liquid
form to help you empty your colon. You will likely have several loose or liquid bowel
movements in the next hours.
Just before the procedure you may be given a type of liquid to drink. This is called
contrast media. It helps the inside of your colon show up more clearly for the X-rays.
Tell your provider if you've had any reactions to contrast media in the past.
During the procedure
Virtual colonoscopy can be done wherever a CT scanner is used. In most cases, it's
done in the radiology department of a hospital or medical center. The scan takes only
about 10 to 15 minutes. This is what happens during the test:
The thin tube will be placed into your rectum. This is used to inflate your colon
with air. You may feel a slight fullness.
A radiologist will put you face up on a table that slides into the CT scanner.
The radiologist will leave the room. The CT scanner will be operated from a separate
control room. You will be able to hear and talk with the staff.
The table will move into and through the scanner. You may hear some whirring and clicking
You may be asked to hold your breath at times.
The scan may need to be repeated while you lie face down.
After the procedure
In most cases, you should be able to return home without help. You can go back to
your normal diet and activities. You will likely not need medicines or special instructions.
Talk with your healthcare provider and the radiology staff if you have any questions.