Colonoscopy is a test that allows your doctor to look at the inner
lining of your
large intestine (rectum and colon). He or she uses a thin, flexible tube
called a colonoscope to look at the colon. A colonoscopy helps find
colon polyps, tumors, and areas of inflammation or
bleeding. During a colonoscopy, tissue samples can be collected (biopsy) and abnormal growths can be taken out.
Colonoscopy can also be used as a screening test to check for cancer or
precancerous growths in the colon or rectum (polyps).
colonoscope is a thin, flexible tube that ranges from
48 in. (125 cm) to
72 in. (183 cm) long. A small
video camera is attached to the colonoscope so that your doctor can take
pictures or video of the large intestine (colon). The colonoscope can be used
to look at the whole colon and the lower part of the small intestine. A test
sigmoidoscopy shows only the
rectum and the lower part of the colon.
Before this test, you will need to clean out your colon (colon prep).
Colon prep takes 1 to 2 days, depending on which type of prep your doctor
recommends. Some preps may be taken the evening before the test. For many people, the prep is worse than the test. The bowel prep may be uncomfortable, and you may feel hungry on the clear liquid diet. Plan to
stay home during your prep time since you will need to use the bathroom often.
The colon prep causes loose, frequent stools and diarrhea so that your colon
will be empty for the test. If you need to drink a special solution
as part of your prep, be sure to have clear fruit juices or soft drinks to
drink after the prep because the solution may have a salty or unpleasant taste.
Colonoscopy is one of many tests that may be used to screen for colon cancer. Other tests include sigmoidoscopy, stool tests, and computed tomographic colonography. Which screening test you choose depends on your risk, your preference, and your doctor. Talk to your doctor about what puts you at risk and what test is best for you.
- Colon Cancer: Which Screening Test Should I Have?
Health Tools help you make wise health decisions or take action to improve your health.
Decision Points focus on key medical care decisions that are important to many health problems.
Colon Cancer: Which Screening Test Should I Have?
Why It Is Done
- Check for colorectal cancer or polyps.
- This test is recommended by the American
Cancer Society (ACS), the American College of Gastroenterologists (ACG), the
American Gastroenterological Association (AGA), and the U.S. Preventive
Services Task Force (USPSTF).
- These groups recommend routine
testing for people age 50 and older who have a normal risk for colorectal
- Your doctor may recommend earlier or more frequent testing if you have a higher risk of colorectal cancer. Talk to your doctor about when you should be tested.
- Check for the cause of blood in the stool or
- Check for the cause of dark or black
- Check for the cause of chronic diarrhea.
for the cause of
iron deficiency anemia.
- Check for the
cause of sudden, unexplained weight loss.
- Check the colon after
abnormal results from a CT scan, MRI, virtual colonoscopy, stool test, or barium enema.
- Watch or treat
inflammatory bowel disease (IBD).
for the cause of long-term, unexplained belly pain.