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A sigmoidoscopy is a diagnostic procedure that allows the doctor to examine the lower one-third of the large intestine. It's helpful in identifying the causes of diarrhea, abdominal pain, constipation, abnormal growths, and bleeding. A short, flexible, lighted tube, called a sigmoidoscope, is inserted into the intestine through the rectum into the lower part of the large intestine. Air is injected into the intestine through the sigmoidoscope to inflate it for better viewing.
A sigmoidscopy can also be used to look inside the rectum and the lower colon for polyps, abnormal areas or cancer. It may also have a tool to remove polyps or tissue samples, which are checked under a microscope for signs of cancer. A sigmoidoscopy and a digital rectal exam (DRE) may be used together to screen for colorectal cancer.