Screening tests range from simple, home-based tests to more sophisticated procedures involving special medical equipment. Your doctor will recommend one of the tests below or possibly a combination of tests:
Digital Rectal Exam
The doctor will don a glove, lubricate a finger, and insert it into the rectum to check for unusual growths or formations. For more information, click here.
Pros and cons: This test only takes about two minutes and is convenient. However, it examines only the lower rectum and should not be the sole means of screening for colorectal cancer.
Fecal Occult Blood Test
Sometimes cancers or polyps bleed, and this test is designed to discover the "occult" or hidden blood in your bowel movement that may not be visible to the naked eye. To take the test, in the privacy of your bathroom, you use a small stick to smear a small amount of stool on a special card. You do this for three days in a row, and then send the cards to your doctor's office or a lab for testing.
Pros and cons: Compared to other techniques, fecal occult blood test is less costly and more convenient. However, it must be repeated every one to two years to be effective as a screening tool. Your doctor may recommend that fecal occult blood testing be combined with another screening technique such as sigmoidoscopy or a barium enema.
A sigmoidoscope is a thin, flexible, lighted tube. Before this procedure, you'll need to take an enema to clean out the bowel. Then the doctor will insert the tube through your rectum into your colon. If he sees a small polyp, he'll remove it. One disadvantage is that because the sigmoidoscope is only about 2 feet long, the doctor can see only part of your colon. For more information, click here.
Pros and cons: Although sigmoidoscopy can be uncomfortable, it usually takes only about 10 to 15 minutes. It is less costly, less time-consuming and less invasive than colonoscopy. However, it examines a smaller portion of the colon and therefore is less effective in detecting cancer. Like colonoscopy, sigmoidoscopy allows your doctor to remove polyps on the spot.
The colonoscope is a longer version of the sigmoidoscope. With it, the doctor can see the entire colon. The day before the test, you'll need to take laxatives to clean out the bowel completely. Just before the test, the doctor will usually give you a sedative to relax you - you'll need someone to drive you home, as you won't be able to drive yourself. The test normally takes about 30 minutes. If the doctor finds a small polyp, he'll remove it by using a wire loop passed through the colonoscope. The polyp is sent to the lab to find out if it's malignant (cancerous) or benign. If your doctor sees a large polyp or tumor, he'll cut a small piece of it (called a biopsy), take it out through the colonoscope, and send it to a lab for testing.
Pros and cons: Colonoscopy is the most effective screening test for detecting colon cancer. However it is also the most costly and time-consuming. Colonoscopy is also the most invasive screening test, and therefore the riskiest. Although it rarely happens (one to three times in every 1,000 procedures), the colon might accidentally become perforated. Many medical experts encourage undergoing colonoscopy, because it is the only test that screens the entire length of the colon.
Barium Enema With Air Contrast
This X-ray test is also called double contrast barium enema. It uses a chalky chemical called barium sulfate and air to outline the lining of the colon and rectum. The doctor gives an enema of barium sulfate, which is held inside the colon while X-rays are taken. Air pumped into the intestine can help sharpen the X-rays. The test takes about 30 minutes. The bowel preparation with laxatives and enemas is similar to the one for colonoscopy.
Pros and cons: Barium enema offers an alternative for people who don't want to undergo sigmoidoscopy or colonoscopy. It provides a picture of the entire colon but may miss small polyps. In addition, if the test uncovers a polyp, you must undergo colonoscopy to have it removed. Cost is usually more than sigmoidoscopy, but less than colonoscopy.
Click here for a glimpse into the future of colorectal cancer screening.