The colon helps your body absorb water and nutrients from the food you eat. It is also where your stool is formed. The last third of your colon is called the sigmoid colon, or the descending colon. It is connected to the anus by the rectum. While a colonoscopy helps the doctor examine the entire colon, sometimes only the sigmoid colon warrants close inspection; this is when a sigmoidoscopy is done.
A sigmoidoscopy, also called a “flexible sigmoidoscopy,” is a procedure that involves using a flexible tube with a light on it to see inside the sigmoid colon. This procedure can help check for ulcers, abnormal cells, polyps, and cancer. Typically, pieces of tissue will be taken as samples to check for any abnormal cell changes.
If you notice any changes in bowel habits, rectal bleeding, abdominal pain, or unexplained weight loss, tell your doctor. These can be signs of various colon diseases and he or she might want to do a sigmoidoscopy to determine the cause of your symptoms. A sigmoidoscopy is also a general screening tool for colon cancer.
You might need to have a sigmoidoscopy every five years after the age of 50, depending on your personal health history as well as whether you have a family history of colorectal cancers.
Sigmoidoscopy preparation is similar to what you would do to prepare for a colonoscopy. One or more enemas may be used approximately two hours prior to the procedure. If your doctor wants the entire colon empty, the preparation will be even more like colonoscopy preparation. For example, you will follow a clear liquid diet for one to three days before the procedure. You may be given a powder laxative to mix with fluid to help empty your intestines. Liquids you can consume include plain coffee or tea, water, fat-free broth, gelatin (like JELL-O), and drinks like Gatorade.
Liquids with red or purple dye should be avoided, as this can look like blood in the colon.
Prior to the procedure, tell your doctor about any other medical conditions you have and all medications and supplements you are taking.
You will be asked to lie on your left side on an examination table. This can be done in the office by a general practitioner or a trained nurse practitioner. A thin, flexible tube called a sigmoidoscope will be inserted into the anus. The tube has a light and a very small camera on the end so images can be transmitted onto a monitor for your doctor to see. The tube will also inflate your colon with some air, to make it easier to examine. You might be uncomfortable, but the procedure is not typically painful. Since you are not usually under sedation during a sigmoidoscopy, your doctor might ask you to shift every so often to allow the scope to be moved more easily.
If the doctor sees any polyps or growths, he or she might remove them with instruments passed through the scope. If there are any abnormal areas in the colon, small pieces of tissue might be removed for further examination.
The risks are minimal, but on rare occasions it is possible for a tear to occur in the colon or the wall of the rectum. If a tissue sample is taken, bleeding could potentially occur in the place where the sample was taken.
The entire procedure takes 10 to 20 minutes, and patients can usually drive themselves to and from the appointment. If you have been given medication to calm or sedate you, you will need someone to drive you home afterward.
Some bloating or cramping is normal after the procedure. If you experience severe abdominal pain, dizziness, bloody stool, or fever, call your doctor immediately. These can be signs of something more serious.
Your doctor will call you with the results if any biopsies were performed. If there is a positive result that warrants further testing, you may need to have the procedure repeated. The test may also need to be repeated if the doctor is concerned about whether he or she got a good-quality picture of the colon and rectum from the test. Talk with your doctor about any questions or concerns you may have about your colorectal health or the results.