Flexible Sigmoidoscopy
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What is the test?
Sigmoidoscopy uses an
endoscope to look inside the lower portion of the large intestine.
The endoscope used for this test is about a half-inch wide and
long enough to reach about two feet into the colon. A sigmoidoscopy
can detect early cancers as well as polyps that could later become
cancerous.
Sigmoidoscopy is an
effective screening test for colon cancer if you have the procedure
done every five years starting at age 50. Alternatively, you
might choose to have a colonoscopy every 10 years to screen for
colon cancer. In either case, it's wise to have a fecal occult
blood test in the years you don't have a sigmoidoscopy or colonoscopy.
A sigmoidoscopy is also useful for evaluating the cause of abdominal
pain, blood in the stool, constipation, and diarrhea.
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How do I prepare
for the test?
Your doctor might ask
you to limit your dinner on the night before the test to clear
liquids such as juice or broth. On the day of the procedure,
you are given one or two enemas 30-60 minutes before the test
to empty your bowels, enabling the doctor to get a clear look
at your large intestine. If you suffer from constipation, your
doctor might also ask you to use a laxative the night before
the test. Try to avoid taking NSAIDs or blood thinners for several
days before this test to reduce the risk of bleeding if any tissue
needs to be biopsied. If you are on medications for diabetes,
ask your doctor about ways to avoid hypoglycemia.
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What happens
when the test is performed?
You wear a hospital
gown for the procedure and lie on your side on a table. After
applying some clear jelly to his or her gloved hand, the doctor
feels the inside of your rectum with a finger, then gently inserts
one end of the sigmoidoscope inside.
The doctor will fill
your intestine with air, which often causes some pain similar
to the cramping you might get when you have gas. As the camera
on the scope transmits pictures to a video screen, your doctor
watches for any suspicious lesions on your bowel lining. If one
appears, he or she might use some small clippers on the end of
the scope to take a tissue sample to check under the microscope.
When the test is finished, the doctor vacuums the air out of
your intestine and slowly removes the tube. The test usually
takes 10-30 minutes.
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What risks are
there from the test?
The risks are minimal.
The chance of perforation is less than for a colonoscopy. A few
people have a small amount of bleeding after the procedure if
a biopsy has been taken.
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Must
I do anything special after the test is over?
You should feel fine
and be able to return to your regular activities immediately
after the test. Call your doctor if you have more than light
bleeding from the rectum or if you have continuing abdominal
pain.
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How
long is it before the result of the test is known?
Your doctor can tell
you right away if there were any polyps or suspicious tissue
in your colon. If biopsies are taken, it usually takes a few
days until a laboratory examines them and gives your doctor a
report. If your doctor finds polyps or cancer in your colon,
you will probably need to have a similar but more comprehensive
procedure called a colonoscopy done on another day. This is because
polyps can be removed only during a colonoscopy. Moreover, discovery
of polyps in the lower portion of the colon during sigmoidoscopy
means there is a greater likelihood that polyps or cancer may
exist in the rest of the colon - and this can be determined only
with a colonoscopy.
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