Sigmoidoscopy (Anoscopy, Proctoscopy)
Anoscopy, proctoscopy, and
sigmoidoscopy tests allow your doctor to look at the inner lining of your
rectum, and the lower part of the
large intestine (colon). These tests are used to look for abnormal growths
(such as tumors or
polyps), inflammation, bleeding,
hemorrhoids, and other conditions (such as
These tests use different
scopes look at different sections of the colon.
- Anoscopy. During
an anoscopy, a short, rigid, hollow tube (anoscope) that may contain a light
source is used to look at the last
2 in. (5 cm) of the colon (anal
canal). Anoscopy can usually be done at any time because it does not require
any special preparation (enemas or laxatives) to empty the
- Proctoscopy. During a proctoscopy, a
slightly longer instrument than the anoscope is used to view the inside of the
rectum. You will usually have to use enemas or laxatives to empty the colon
before the test is done.
During a sigmoidoscopy, a lighted tube that may be either rigid or flexible is
inserted through the anus. Your doctor can remove small growths and collect
tissue samples (biopsy) through a sigmoidoscope. You will have to use
enemas or laxatives (or both) to empty the colon before the test is done.
- The flexible sigmoidoscope is about
2.3 ft (70 cm) long and
0.5 in. (1 cm) wide with a
lighted lens system. This instrument allows your doctor to see around bends in
the colon. A flexible sigmoidoscope allows a more complete view of the lower
colon than a rigid scope and usually makes the examination more comfortable.
The flexible sigmoidoscope generally has replaced the rigid
- The rigid sigmoidoscope is used less often. It is about
10 in. (25 cm) to
12 in. (32 cm) long and
1 in. (2.5 cm) wide. It allows
your doctor to look into the rectum and the bottom part of the colon, but it
does not reach as far into the colon as the flexible sigmoidoscope.
Flexible sigmoidoscopy is one of many tests that may be used to screen for colon cancer. 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.
information on screening tests for colon cancer, see:
- 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
These tests are done to:
- Detect problems or diseases of the anus,
rectum, or lower large intestine (sigmoid colon). These tests are often done to
investigate symptoms such as unexplained bleeding from the rectum, long-lasting
diarrhea or constipation, blood or pus in the stool, or lower abdominal
- Remove polyps or hemorrhoids.
- Monitor the growth of polyps or the treatment of
inflammatory bowel disease.
- Screen for
colon cancer or polyps.