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April 2021

Testing for Colorectal Cancer at Home

A fecal occult blood test (FOBT) is one of several tests your healthcare provider may use to screen for colorectal cancer. This take-home test looks for blood in the stool that you can’t see with the naked eye, often caused by bleeding in the digestive tract. A positive result doesn’t mean you have colorectal cancer. Other conditions—such as polyps, hemorrhoids, diverticulitis, and ulcers—can also trigger a positive result.

Three types of FOBTs detect blood in different ways. They include a:

  1. Guaiac-based fecal occult blood test (gFOBT)

  2. Fecal immunochemical test (FIT)

  3. FIT-DNA test

People who take one of these tests need to repeat it every year or every 3 years, depending on the test.

What you need to do

Your provider will give you a test kit along with instructions. The instructions may vary based on the type of kit, but most FOBTs involve:

  • Collecting multiple stool samples

  • Using a device to swipe the sample onto a test card or slide

  • Labeling and sealing the sample

  • Sending the samples to your provider or lab

For best results

Many people find these take-home tests easier than some other colorectal tests, like a colonoscopy. These tips can help you take your at-home stool test:

  • Ask your provider whether you need to prepare for the test. For the guaiac-based test, you may need to avoid certain medicines, supplements, and foods that can affect the test results.

  • Make sure you have all the supplies you need. Kits typically include test cards; a collection device, such as a brush or wooden applicator; and an envelope to return the samples.

  • Make sure you follow the instructions included with your kit.

  • Call your provider’s office if you have any questions about how to use it.

If your test is positive, meaning it found certain changes or blood, your healthcare provider likely will order a colonoscopy to identify the cause and site of the bleeding.

Is this test right for you?

The American Cancer Society recommends that people who are at average risk for colorectal cancer start screenings at age 45. In addition to stool-based testing, your provider may recommend other screenings methods—such as colonoscopy, virtual colonoscopy, or flexible sigmoidoscopy—that visualize the colon and rectum.

Each screening method has pros and cons. Talk with your provider about which tests are best for you and how often you should be tested.



Online Medical Reviewer: Brian McDonough, MD
Online Medical Reviewer: Ray Turley, BSN, MSN
Date Last Reviewed: 2/1/2021
© 2000-2021 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.
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