colon polyps are large and cause bleeding or pain, the
only way to know if you have polyps is to have one or more tests that explore
the inside surface of your colon.
Several tests can be used to
detect colon polyps. Two of these exams,
flexible sigmoidoscopy and
colonoscopy, also can be used to collect tissue
samples (called a
biopsy) or to remove colon polyps. All the tests may
be used to screen for colon polyps and colon cancer and as follow-up tests
after colon polyps have been removed. There are two basic types of tests—stool
tests and tests that look inside your body.
Fecal occult blood test (FOBT). A
fecal occult blood test (FOBT) is done to look for
microscopic amounts of blood in stool. FOBT is a simple, low-cost screening
tool for colon polyps or colon cancer. FOBT has been shown in studies to reduce
the number of deaths from colon cancer. By itself, an FOBT is not evidence of
colon polyps or colon cancer. And a negative FOBT (no blood found) does not
mean that you do not have
polyps or colorectal cancer. If a fecal occult blood test is
positive for blood in the stool, it is important to have a colonoscopy to help
your doctor find the source of the blood and remove polyps if they are
Fecal immunochemical test (FIT). This
test also looks for blood in the stool, but it is more specific than the FOBT.
There aren't as many restrictions on what you can eat before having this test,
and fewer stool samples are required. If the test is positive for blood in the
stool, you may need to have a colonoscopy.
Stool DNA test (sDNA). This test checks for changes to the cells in the colon
by looking at DNA in the stool. Certain kinds of changes in cell DNA
happen when you have cancer. Like the other stool tests, if your test is
positive, you may need to have a colonoscopy.
Tests that look inside your body
Flexible sigmoidoscopy.Flexible sigmoidoscopy allows the doctor to look at
the lower third of the colon. During a sigmoidoscopy exam, samples of any
growths can be collected (biopsied). And precancerous and cancerous polyps can
sometimes be removed.
screening method lets a doctor inspect the entire colon for polyps and cancer.
colonoscopy, samples of any growths can be collected
(biopsied). And precancerous and cancerous polyps usually can be
Computed tomographic colonography (CTC).
This test is also called
virtual colonoscopy. A computer and X-rays make a
detailed picture of the colon to help the doctor look for polyps. If this test
finds polyps, you may need to have a colonoscopy.