|What happens when the test is performed?
- You may receive a
sedative through an IV (see "Sedatives and anesthesia,"
page 8). You wear a hospital gown for the test and lie
on your side on a table.After putting on a glove and
applying some clear jelly to the outside of it, the doctor
feels the inside of your rectum with a finger. He or
she gently inserts one end of the colonoscope into
your rectum. The colonoscope is a type of endoscope
that is about half an inch wide and a little more than
5 feet long so it can reach the entire length of your
large intestine (see "Endoscopes," page 27).
The doctor fills your intestine with air so that the
camera at the end of the colonoscope gets a good view.
If you didn't receive a sedative, you might feel a cramplike
pain - similar to the cramping you might get
when you have gas-when air is pumped into your
colon. Images of the interior of your colon appear on
a video screen. If your doctor sees a suspicious place
on the bowel lining, he or she might use some small
clippers on the end of the scope to take a biopsy.
If your doctor sees a polyp, he or she removes it
with a loop of wire pushed through the colonoscope.
The doctor tightens the loop around the polyp's stem
and sends a brief electric current through the wire
to burn the stem and separate it from your intestine.
This process isn't painful because there are few nerve
endings in the stem of the polyp. The polyp can be
removed using vacuum pressure on the colonoscope
or another tool on the end of the scope.When the
doctor is finished, he or she sucks the extra air out of
your intestine and gently pulls the colonoscope out.
The test usually takes 20-90 minutes, depending on
whether any polyps are removed.