Flexible sigmoidoscopy lets your doctor examine the lining of the rectum and a portion of the colon (large intestine) by inserting a flexible tube about the thickness of your finger into the anus and slowly advancing it into the rectum and lower part of the colon.
Your doctor will tell you what cleansing routine to use. In general, preparation consists of one or two enemas prior to the procedure but could include laxatives or dietary modifications as well. However, in some circumstances your doctor might advise you to forgo any special preparation. Because the rectum and lower colon must be completely empty for the procedure to be accurate, it's important to follow your doctor's instructions carefully.
Flexible sigmoidoscopy is usually well-tolerated. You might experience a feeling of pressure, bloating or cramping during the procedure. You will lie on your side while your doctor advances the sigmoidoscope through the rectum and colon. As your doctor withdraws the instrument, your doctor will carefully examine the lining of the intestine.
Your doctor will explain the results to you when the procedure is done. You might feel bloating or some mild cramping because of the air that was passed into the colon during the examination. This will disappear quickly when you pass gas. You should be able to eat and resume your normal activities after leaving your doctor's office or the hospital, assuming you did not receive any sedative medication.