Flexible sigmoidoscopy is a procedure in which a trained medical professional uses a flexible, narrow tube with a light and tiny camera on one end, called a sigmoidoscope or scope, to look inside your rectum and lower colon, also called the sigmoid colon and descending colon.  A sigmoidoscopy covers only the lower part of the colon, also known as the rectum and sigmoid colon.  A flexible sigmoidoscopy exam can help your doctor explore possible causes of abdominal pain, rectal bleeding, changes in bowel habits, chronic diarrhea and other intestinal problems. There is a lower risk of direct harm such as perforation with sigmoidoscopy compared with colonoscopy.  It is inserted gently into the anus and advanced slowly into the rectum and the lower colon.  In most instances, you will be lying on your left side while the instrument is advanced through the rectum and the colon under direct vision on a TV monitor.  There may be a sensation of fullness, bloating, pressure, or cramping during the procedure.  As the instrument is withdrawn, a careful examination is made of the lining of the colon.  The procedure usually takes only 5 to 15 minutes.  In order to obtain accurate results, the rectum and the lower colon must be completely clean of stool.  A health care professional will give you written bowel prep instructions to follow at home before the procedure.  Flexible sigmoidoscopy is generally well tolerated and rarely causes any significant pain.