To look at the inside of the rectum and part of the colon for cancer or polyps, Massachusetts General Hospital Digestive Healthcare Center physicians use a procedure called a sigmoidoscopy.
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A sigmoidoscope is a thin, flexible, lighted tube about the thickness of a finger. During a sigmoidoscopy, your doctor will place the sigmoidoscope into the lower part of your colon through your rectum. This procedure allows your doctor to look at the inside of the rectum and part of the colon for cancer or polyps.
Be sure your doctor is aware of any medicines you are taking, as you may need to change how you take them before the test. The day before the test, you will need to take some medicine to clean out your colon and rectum so the doctor can clearly see the lining.
A sigmoidoscopy usually takes 10 to 20 minutes. During the test, your doctor will place a sigmoidoscope in the lower part of your colon through your rectum. Because the tube is only about two feet long, your doctor will be able to see about half of your colon.
If a small polyp is found, your doctor may remove it during this test. This can be done with tools used through the scope. If a polyp or colorectal cancer is found during the test, you will need to have a colonoscopy to look for polyps or cancer in the rest of your colon.
A sigmoidoscopy can be uncomfortable, but it should not be painful. Most people do not need to be sedated for this test, but this is an option you can discuss with your doctor. Sedation may make the test easier, but you will need some time to recover as well as someone with you to take you home after the test.