What is a colonoscopy?
A colonoscopy (koh-luh-NAH-skuh-pee) allows a specially trained doctor called a gastroenterologist to look inside the entire large intestine. The procedure enables the physician to see things such as inflamed tissue, abnormal growths, and ulcers. It is most often used to look for early signs of cancer in the colon and rectum. It is also used to look for causes of unexplained changes in bowel habits and to evaluate symptoms like abdominal pain, rectal bleeding, and weight loss.
What is the colon?
The colon, or large bowel, is the last portion of your digestive tract, or gastrointestinal tract. The colon is a hollow tube that starts at the end of the small intestine and ends at the rectum and anus. The colon is about 5 feet long, and its main function is to store unabsorbed food waste and absorb water and other body fluids before the waste is eliminated as stool.
Preparation
You will be given instructions in advance that will explain what you need to do to prepare for your colonoscopy (bowel preparation instructions). Your colon must be completely empty for the colonoscopy to be thorough and safe. Please refer to the prescribed bowel preparation for specific details.
Procedure
For the colonoscopy, you will lie on
your left side on the examining table. You will be given
sedation that will keep you safe and comfortable during the exam. The
gastroenterologist and/or anesthesiologist will
monitor your vital signs, look for any signs of discomfort, and
make adjustments as needed.
The
gastroenterologist will then insert a long, flexible, lighted tube into
your rectum and slowly guide it into your colon. The tube is
called a colonoscope (koh-LON-oh-skope).
The scope transmits an image of the inside of the colon onto a
video screen so the doctor can carefully examine the lining of
the colon. The scope bends so the doctor can move it around the
curves of your colon. The scope blows air into your colon and inflates it,
which helps give the doctor a better view. Most patients do not
remember the procedure afterward.
The
gastroenterologist can remove most abnormal growths in your colon, like
a polyp, which is a growth in the lining of the bowel. Polyps
are removed using tiny tools passed through the scope. Most
polyps are not cancerous, but they could turn into cancer. Just
looking at a polyp is not enough to tell if it is cancerous. The
polyps are sent to a lab for testing. By identifying and
removing polyps, a colonoscopy likely prevents most cancers from
forming.
The
gastroenterologist can also remove tissue samples to test in the lab for
diseases of the colon (biopsy). In addition, if any bleeding
occurs in the colon, the doctor can pass a laser, heater probe,
electrical probe, or special medicines through the scope to stop
the bleeding. The tissue removal and treatments to stop bleeding
usually do not cause pain. In many cases, a colonoscopy allows
for accurate diagnosis and treatment of colon abnormalities
without the need for a major operation.
When the
doctor has finished, the colonoscope
is slowly withdrawn while the lining of your bowel is carefully
examined. Bleeding and puncture of the colon are possible but
extremely
uncommon complications of a colonoscopy.
A colonoscopy usually takes 20 to 40 minutes. The sedative should keep you from feeling discomfort
during the exam. You may feel some cramping or the sensation of
having gas after the procedure is completed, but it usually
stops within an hour.
Rarely, some people experience severe abdominal pain, fever,
bloody bowel movements, dizziness, or weakness afterward. If you
have any of these side effects, contact your physician
immediately. Read your discharge instructions carefully.
Medications such as blood-thinners may need to be stopped for a
short time after having your colonoscopy, especially if a biopsy
was performed or polyps were removed. Full recovery by the next
day is normal and expected and you may return to your regular
activities.
For more
information
American College of
Gastroenterology
P.O. Box 342260
Bethesda, MD 20827–2260
Phone: 301–263–9000
Fax: 301–263–9025
Email:
info@acg.gi.org
Internet:
www.acg.gi.org
International Foundation for
Functional Gastrointestinal Disorders
P.O. Box 170864
Milwaukee, WI 53217–8076
Phone: 1–888–964–2001 or 414–964–1799
Fax: 414–964–7176
Email:
iffgd@iffgd.org
Internet:
www.iffgd.org
National Digestive Diseases
Information Clearinghouse
2 Information Way
Bethesda, MD 20892–3570
Email:
nddic@info.niddk.nih.gov
The National Digestive Diseases
Information Clearinghouse (NDDIC) is a service of the National
Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).
The NIDDK is part of the National Institutes of Health under the
U.S. Department of Health and Human Services. Established in
1980, the Clearinghouse provides information about digestive
diseases to people with digestive disorders and to their
families, health care professionals, and the public. The NDDIC
answers inquiries, develops and distributes publications, and
works closely with professional and patient organizations and
Government agencies to coordinate resources about digestive
diseases.
Publications produced by the Clearinghouse are carefully
reviewed by both NIDDK scientists and outside experts. This
publication was reviewed by Michael Wallace, M.D., Mayo Clinic.
This publication is not copyrighted. The Clearinghouse
encourages users of this publication to duplicate and distribute
as many copies as desired.
NIH Publication No. 06–4331
November 2005