Advantages of VC
Disadvantages of VC
For More Information
Virtual colonoscopy (VC) uses x-rays and computers to produce
two- and three-dimensional images of the colon (large intestine)
from the lowest part, the rectum, all the way to the lower
end of the small intestine and display them on a screen. The
procedure is used to diagnose colon and bowel disease, including
polyps, diverticulosis, and cancer. VC can be performed with
computed tomography (CT), sometimes called a CAT scan, or
with magnetic resonance imaging (MRI).
While preparations for VC vary, you will usually be asked
to take laxatives or other oral agents at home the day before
the procedure to clear stool from your colon. You may also
be asked to use a suppository to cleanse your rectum of any
remaining fecal matter.
VC takes place in the radiology department of a hospital
or medical center. The examination takes about 10 minutes
and does not require sedatives. During the procedure,
* The doctor will ask you to lie on your back on a table.
* A thin tube will be inserted into your rectum, and air
will be pumped through the tube to inflate the colon for better
* The table moves through the scanner to produce a series
of two-dimensional cross-sections along the length of the
colon. A computer program puts these images together to create
a three-dimensional picture that can be viewed on the video
* You will be asked to hold your breath during the scan to
avoid distortion on the images.
* The scanning procedure is then repeated with you lying
on your stomach.
After the examination, the information from the scanner must
be processed to create the computer picture or image of your
colon. A radiologist evaluates the results to identify any
You may resume normal activity after the procedure, although
your doctor may ask you to wait while the test results are
analyzed. If abnormalities are found and you need conventional
colonoscopy, it may be performed the same day.
In a conventional colonoscopy, the doctor inserts a colonoscope--a
long, flexible, lighted tube--into the patient's rectum and
slowly guides it up through the colon. Pain medication and
a mild sedative help the patient stay relaxed and comfortable
during the 30- to 60-minute procedure. A tiny camera in the
scope transmits an image of the lining of the colon, so the
doctor can examine it on a video monitor. If an abnormality
is detected, the doctor can remove it or take tissue samples
using tiny instruments passed through the scope.
For more information about conventional colonoscopy, please
view our Colonoscopy
VC is more comfortable than conventional colonoscopy for some
people because it does not use a colonoscope. As a result,
no sedation is needed, and you can return to your usual activities
or go home after the procedure without the aid of another
person. VC provides clearer, more detailed images than a conventional
x-ray using a barium enema, sometimes called a lower gastrointestinal
(GI) series. It also takes less time than either a conventional
colonoscopy or a lower GI series.
The doctor cannot take tissue samples or remove polyps during
VC, so a conventional colonoscopy must be performed if abnormalities
are found. Also, VC does not show as much detail as a conventional
colonoscopy, so polyps smaller than 10 millimeters in diameter
may not show up on the images.
American College of Gastroenterology (ACG)
4900-B South 31st Street
Arlington, VA 22206-1656
Phone: (703) 820-7400
Fax: (703) 931-4520
International Foundation for Functional Gastrointestinal
P.O. Box 170864
Milwaukee, WI 53217
Phone: 1-888-964-2001 or (414) 964-1799
Fax: (414) 964-7176