What is the Screening Test For Colon Cancer?

Dr. Tyler Buckley

March 28, 2023

Tyler Buckley

The screening test for colon cancer is a procedure to look inside your large intestine. The tests are safe and effective in detecting cancer and polyps before they become serious problems.

Doctors recommend regular screening starting at age 45 for most healthy adults. If you have a family history of colon cancer or increased risk, talk to your doctor about getting tested sooner and more often.


A flexible sigmoidoscopy is a test that uses a flexible tube called a sigmoidoscope to examine the lower part of your colon. It is used to help diagnose inflammatory bowel disease (IBD) and screen for colorectal cancer.

During this procedure, your doctor inserts a thin, flexible tube into your anus and advances it through your rectum and the lower part of your colon. It contains a light and camera, which relays images of the inner lining to a monitor.

Your doctor may be able to remove polyps with this device or obtain tissue samples for later biopsy. Biopsies are a significant way to check for precancerous growths, which can lead to cancer.

You must prepare for this procedure by emptying your bowels with an enema before the exam. Your provider will advise you on how to do this and recommend a clear liquid diet the day before the test.


Colonoscopy is a test that looks at the colon, and the lining of the lower part of the digestive tract called the rectum. It allows your doctor to look for polyps and other problems leading to colon cancer.

The test can also help identify the cause of symptoms, like blood in stools or diarrhea, and can help find the source of rectal bleeding. It can be used as a follow-up for a digital rectal exam or after a positive fecal occult blood test.

A flexible tube is inserted into the rectum and sigmoid colon to allow the doctor to see the lining of your colon. The doctor may use a camera in the box to look for polyps or abnormalities and will take a tissue sample for testing.

Most people feel comfortable during the procedure and recover well. Occasionally, minor problems can persist. These usually go away in 24 hours or less.

CT Colonography

The screening test for colon cancer is called CT Colonography. It uses computer technology and X-rays to produce 2D and 3D pictures of your colon and rectum.

You lie on the examining table in a particular room during this test. Your doctor puts a slender tube into your rectum. Air is pumped through the line to inflate it, so your doctor can see more clearly during the exam.

Your doctor may also remove any abnormal tissue on the X-rays, such as polyps or cancer. If any polyps are removed, a tissue biopsy can be done to test for cancer.

Before the test, you should clean out your bowel carefully, ensuring that it is empty of any food or waste, by following instructions given by your doctor. This will ensure that you get the best imaging possible. Follow these instructions to ensure the test is performed correctly and your results may be accurate.

Stool Tests

The screening test for colon cancer looks at the lining of your colon and rectum (a small part of your large intestine). It can find precancerous polyps, tumors, or colorectal cancer.

It can also show you how well your digestive tract absorbs fats and meat fibers, which can help you change your diet. It also checks for any infections in your digestive tract, such as yeast infections or parasites.

Stool tests can be done at home with a kit your doctor gives you. Some kits offer results in minutes; others are mailed to a lab for testing.

Your doctor will talk with you about any abnormal results. Some medicines can change the results of a stool analysis.

A fecal occult blood test or FOBT detects tiny amounts of hidden blood in your stool. This may be an early sign of colon cancer or polyps that bleed. The test is usually done every year for people at average risk.