What is a colonoscopy?
Colonoscopy enables your doctor to examine the lining of your colon
(large intestine) for abnormalities by inserting a flexible tube as
thick as your finger into your anus and slowly advancing it into the
rectum and colon. If your doctor has recommended a colonoscopy, this
brochure will give you a basic understanding of the procedure - how
it's performed, how it can help, and what side effects you might experience.
It can't answer all of your questions since much depends on the individual
patient and the doctor. Please ask your doctor about anything you
What preparation is required?
Your doctor will tell you what dietary restrictions to follow and
what cleansing routine to use. In general, the preparation consists
of either consuming a large volume of a special cleansing solution
or clear liquids and special oral laxatives. The colon must be completely
clean for the procedure to be accurate and complete, so be sure to
follow your doctor's instructions carefully.
Can I take my current medications?
Most medications can be continued as usual, but some medications can
interfere with the preparation or the examination. Inform your doctor
about medications you're taking, particularly aspirin products, arthritis
medications, anticoagulants (blood thinners), insulin or iron products.
Also, be sure to mention allergies you have to medications. Alert
your doctor if you require antibiotics prior to dental procedures,
because you might need antibiotics before a colonoscopy as well.
What happens during colonoscopy?
Colonoscopy is well-tolerated and rarely causes much pain. You might
feel pressure, bloating or cramping during the procedure. Your doctor
might give you a sedative to help you relax and better tolerate any
discomfort. You will lie on your side or back while your doctor slowly
advances a colonoscope through your large intestine to examine the
lining. Your doctor will examine the lining again as he or she slowly
withdraws the colonoscope. The procedure itself usually takes 15 to
60 minutes, although you should plan on two to three hours for waiting,
preparation and recovery. In some cases, the doctor cannot pass the
colonoscope through the entire colon to where it meets the small intestine.
Although another examination might be needed, your doctor might decide
that the limited examination is sufficient.
What if the colonoscopy shows something abnormal?
If your doctor thinks an area needs further evaluation, he or she
might pass an instrument through the colonoscope to obtain a biopsy
(a sample of the colon lining) to be analyzed. Biopsies are used to
identify many conditions, and your doctor might order one even if
he or she doesn't suspect cancer. If colonoscopy is being performed
to identify sites of bleeding, your doctor might control the bleeding
through the colonoscope by injecting medications or by coagulation
(sealing off bleeding vessels with heat treatment). Your doctor might
also find polyps during colonoscopy, and he or she will most likely
remove them during the examination. These procedures don't usually
cause any pain.
What are polyps and why are they removed?
Polyps are abnormal growths in the colon lining that are usually benign
(noncancerous). They vary in size from a tiny dot to several inches.
Your doctor can't always tell a benign polyp from a malignant (cancerous)
polyp by its outer appearance, so he or she might send removed polyps
for analysis. Because cancer begins in polyps, removing them is an
important means of preventing colorectal cancer.
How are polyps removed?
Your doctor might destroy tiny polyps by fulguration (burning) or
by removing them with wire loops called snares or with biopsy instruments.
Your doctor might use a technique called "snare polypectomy"
to remove larger polyps. That technique involves passing a wire loop
through the colonoscope and removing the polyp from the intestinal
wall using an electrical current. You should feel no pain during the
What happens after a colonoscopy?
Your physician will explain the results of the examination to you,
although you'll probably have to wait for the results of any biopsies
performed. If you have been given sedatives during the procedure,
someone must drive you home and stay with you. Even if you feel alert
after the procedure, your judgment and reflexes could be impaired
for the rest of the day. You might have some cramping or bloating
because of the air introduced into the colon during the examination.
This should disappear quickly when you pass gas.
You should be able to eat after the examination, but your doctor might
restrict your diet and activities, especially after polypectomy.
What are the possible complications of colonoscopy?
Colonoscopy and polypectomy are generally safe when performed by doctors
who have been specially trained and are experienced in these procedures.
One possible complication is a perforation, or tear, through the bowel
wall that could require surgery. Bleeding might occur at the site
of biopsy or polypectomy, but it's usually minor. Bleeding can stop
on its own or be controlled through the colonoscope; it rarely requires
follow-up treatment. Some patients might have a reaction to the sedatives
or complications from heart or lung disease. Although complications
after colonoscopy are uncommon, it's important to recognize early
signs of possible complications. Contact your doctor if you notice
severe abdominal pain, fever and chills, or rectal bleeding of more
than one-half cup. Note that bleeding can occur several days after
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ASGE - The Source for Colonoscopy and Endoscopy
The preceding information is intended only to provide general information
and not as a definitive basis for diagnosis or treatment in any particular
case. It is very important that you consult your doctor about your