During the test, a gown is worn so that the lower half of your body is exposed. You are positioned on your left side with your knees drawn toward your chest.
Following a digital rectal exam, the sigmoidoscope will be inserted. This is a flexible fiberoptic tube about 20 inches long. The scope is gently advanced into the colon. Air is introduced into the scope to aid in viewing. The air may cause the urge to defecate. As the sigmoidoscope is slowly removed, the lining of the bowel is carefully examined. A channel in the scope allows for the passage of forceps for biopsies.