This test can find both colorectal polyps and cancer.

During this test, the doctor looks at part of the colon and rectum with a sigmoidoscope - a flexible, lighted tube about the thickness of a finger with a small video camera on the end. Images from the scope are viewed on a display monitor.

Using the sigmoidoscope, your doctor can view the inside of the rectum and part of the colon to detect (and possibly remove) any abnormality. Because the sigmoidoscope is short, the doctor is able to see the entire rectum but only less than half of the colon.

Before the test: You will need to have a bowel preparation to clean out your lower colon and rectum so your doctor can view their linings. Most colon cancer screenings require strong laxatives, enemas, and/or special diets (such as drinking only clear liquids) prior to the procedure. Your doctor will give you specific instructions to follow that are appropriate for this type of screening. Be sure your doctor is aware of any medicines you are taking, as you may need to change how you take them before the test.

During the test: The test usually takes 10-20 minutes. Most people do not need to be sedated, but this may be an option you can discuss with your doctor. Sedation may make the test less uncomfortable, but it requires more recovery time and requires someone to take you home after the test.

You will likely be placed on a table on your left side with your knees positioned near your chest. Your doctor should do a digital rectal exam before inserting the lubricated sigmoidoscope. Air will be placed into the sigmoid colon through the sigmoidoscope so the doctor can see the colon better. If a small polyp is found your doctor may remove it with a small instrument passed through the scope. The polyp will be sent to a lab to be examined by a pathologist. If a pre-cancerous polyp or cancer is found during the test, you will require a colonoscopy at a later date to look for polyps or cancer in the rest of the colon.

Possible side effects: Many people consider the bowel preparation to be the most unpleasant part of the test, as it usually requires you to be in the bathroom quite a bit. Because of the air put into the colon, you might feel pressure and slight cramping in your lower abdomen. Be sure to let your doctor know if you feel pain during the procedure. To ease discomfort and any urge to have a bowel movement, it helps to breathe deeply and slowly through your mouth. You will feel better after the test once the air leaves your colon. You may see a small amount of blood in your first bowel movement after the test. Bleeding and puncture of the colon are possible complications, but they are very uncommon.