Sigmoidoscopy (Anoscopy, Proctoscopy)

Anoscopy, proctoscopy, and sigmoidoscopy tests allow your doctor to look at the inner lining of your Reference anus Opens New Window, Reference rectum Opens New Window, and the lower part of the Reference large intestine Opens New Window Reference Opens New Window (colon). These tests are used to look for abnormal growths (such as tumors or Reference polyps Opens New Window), inflammation, bleeding, Reference hemorrhoids Opens New Window, and other conditions (such as Reference diverticulosis Opens New Window).

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 colon.
• Proctoscopy. During a proctoscopy, a slightly longer instrument than the anoscope is used to view the inside of the rectum. You will probably have to use an enema or laxative to empty the colon before the test is done.
  • The proctoscope 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.
• Sigmoidoscopy. 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 (Reference biopsy Opens New Window) through a sigmoidoscope. You will have to use an enema or laxative (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 sigmoidoscope.

Flexible sigmoidoscopy is one of many tests that may be used to screen for colon cancer. Reference 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.

For more information on screening tests for colon cancer, see:

Opens New Window Colon Cancer: Which Screening Test Should I Have? Opens New Window

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