A sigmoidoscopy helps your doctor look at the lower part of your large intestine (sigmoid colon). The test is done using a lighted viewing scope (sigmoidoscope).

During a sigmoidoscopy, puffs of air sometimes are blown through the scope to open the colon so that your doctor can see more clearly. Your doctor will move the scope as far as possible into your lower colon. Then the scope is slowly withdrawn while the colon is carefully inspected. Your doctor may also insert tiny instruments through the scope to get tissue samples (biopsy) or to take out growths.