Frequently Asked Question
about Virtual Colonoscopy
Virtual Colonoscopy (CV) is a new method that allows doctors to look at the
large bowel (colon) to detect polyps and cancers. Polyps are small growths
in the colon that may become cancerous if they are not removed. Virtual Colonoscopy
is a recently developed technique that uses a CT scanner and Virtual Reality
software to look inside the body without having to insert a long tube (Conventional
Colonoscopy) into the colon and without the need for sedation (an intravenous
injection requiring 6-8 hours of restricted activity following the procedure)
or without having to fill the colon with liquid barium/air (Double Contrast
Barium Enema). Research performed at Boston University and elsewhere has shown
that Virtual Colonoscopy is better able to see polyps than a Double Contrast
Barium Enema and is nearly as accurate as Conventional Colonoscopy for polyps
most likely capable of becoming cancerous. In addition, most patients report
that the Virtual Colonoscopy technique is more comfortable than either Double
Contrast Barium Enema or Conventional Colonoscopy.
Why Is Having a VC Important?
Colorectal cancer (CRC) is a leading cause of cancer-related death in the United
States,
second only to lung cancer.
Approximately 140,000 cases of colon cancer will be diagnosed in the U.S. this
year and
60,000 patients will die of the disease. Colon cancer can be prevented if polyps
are
discovered and removed early. Tumors (masses of abnormal cells) take years
to develop.
Initially, a cell from the colon starts to multiply abnormally and forms a
benign (noncancerous)
polyp that can remain harmless for a long time before becoming an aggressive
cancer. Polyps, when detected, can be removed preventively. Nevertheless, individuals
at
greatest risk of developing colorectal cancer remain largely under screened.
This is due, in
part, to poor public awareness and acceptance of current screening techniques.
In fact, 7
out of 10 individuals for whom screening is indicated, will refuse to undergo
colon screening for a multitude of reasons.
What Are the Current Methods Used to Detect Polyps?
There are several tests that are used to try and detect polyps. Several government
agencies
as well as the American Cancer Society recommend that patients undergo a test
that allows
the doctor to see the entire colon at age 50 and then every three to five years
thereafter.
Currently there are two accepted methods for seeing the entire colon: the Conventional
Colonoscopy and the Double Contrast Barium Enema. Other tests like the Flexible
Sigmoidoscope or Rigid Sigmoidoscope, which can only see a small portion of
the large
bowel (colon), are considered inferior tests.
Although the Double Contrast Barium Enema and Conventional Colonoscopy permit
visualization of the entire colon, the sensitivity of Double Contrast Barium
Enema is far from
optimal and is uncomfortable both for patient and examiner. Conventional Colonoscopy
is
associated with increased risk and is costly. Conventional Colonoscopy is unable
to see the
entire colon in one out of ten people.
In addition, Conventional Colonoscopy may cause an injury of the colon (tear
or perforation)
in one out of 1500 patients. Medication given into the vein (intravenous sedation)
is usually
required to make the exam bearable and therefore patients cannot resume normal
activities
immediately after the test. The introduction of a safe, noninvasive and effective
method of
detecting colorectal polyps and cancers will greatly improve the early detection
of colon
cancer while it can be easily treated.
How Is it Done?
Virtual Colonoscopy uses a state-of-the-art 16-slice Multi-detector Computed
Tomography
(MDCT or CAT scan) of the abdomen and pelvis. This allows radiologists (special
physicians with advanced training in x-ray imaging) to create pictures on the
computer that
look similar to those seen by Conventional Colonoscopy. Patients need a cleansing
preparation of their bowel prior to the test. The day of the test they come to
our Bellevue
Tower for their CT scan. The actual Virtual Colonoscopy procedure will begin
by inserting a
small flexible tube into the rectum, so that air can be introduced. A CT scan
is then
performed while patients lie comfortably on their back and then on their stomach.
The total
time required for the study is approximately 10-20 minutes. Because sedation
is not
required, patients are free to leave our CT center immediately without the need
for
observation or recovery. Patients can resume normal activities immediately after
the
procedure and can eat, work or drive without a delay. The radiologist will analyze
the CT
data to detect colon polyps or cancers. Your physician will receive a copy of
your report
within 48 hours.
Is it Painful?
When air is introduced in the colon some patients experience minimal temporary
abdominal
cramping or “gas pains.” A widely used intravenous injection to relax
the bowel can also be
given to help reduce the gas pains, but this is usually not necessary. Relaxing,
by taking in
slow deep breaths, will help to alleviate any discomfort.
When and How Often Do I Need to Have a Test to Screen for
Polyps?
Patients over 50 years old should be tested every 3-5 years with a Barium Enema,
Conventional Colonoscopy, or Virtual Colonoscopy.
What Is Our Screening Referral Policy?
Washington Imaging Services recognizes the popularity that screening has achieved
in the
community and its availability on a self-referral basis. However, as ethical
physicians we are
obliged to offer services for which there is scientific basis and to refrain
from advertising that
plays upon the population’s fears or is misleading.
For that reason, WIS offers our screening services to our patients
with a referral request from their physician. We believe this best
allows for an intelligent decision as to the value
of any medical procedure selected.
