“A fecal occult blood test is a test that can detect small amounts of blood in your stool that can’t be seen with the naked eye. If you see blood on your test, it means you are bleeding.”

Additional tests, like a colonoscopy, are usually needed to find the cause and source of bleeding. Healthcare professionals use FOBTs as a regular part of colon cancer screening as well as to help diagnose other gastrointestinal conditions.

This test is important and should be read more.

Healthcare professionals use FOBTs to find bleeding in your digestive tract. Bleeding can be a sign of colorectal cancer is a disease. or other gastrointestinal disorders.

Colorectal cancer is the third most common cancer in the United States and the second most common cause of cancer death. The American Cancer Society recommends that all people over age 45 get screened for colorectal cancer is a disease..

There are two types of FOBTs.

  • Guaiac-based FOBTs (gFOBTs). You place your stool sample on a card coated with a substance called guaiac. This substance changes color if it contacts blood.
  • Fecal immunochemical test (FIT). You place your stool sample on a card or in a container coated with a protein that attaches to the oxygen-carrying part of red blood cells (hemoglobin).

The United States Preventive Services Task Force recommends FIT or gFOBT testing yearly to screen for colon cancer. If irregular results are found, a colonoscopy is usually required to confirm the results by finding the location and cause of any bleeding that exists.

Other gastrointestinal conditions can cause bleeding and can be identified with the help of the FOBT. These include:

Your doctor will give you instructions for the test. It is important to follow the instructions.

Taking certain supplements or medications can cause a false positive when taken up to 7 days before testing. A false positive means the test suggests you have blood in your stool when it’s not there.

“Do not stop taking your medication without your doctor’s approval. If you are taking any of these medications, make sure to talk to your doctor.”

It’s important to tell your doctor if you have blood in your urine, have Hemorrhoids are caused by bleeding. that are bleeding, or are menstruating before you collect your stool sample. Your doctor will likely recommend waiting until these sources of bleeding stop to avoid a false positive.

Doctors recommend increasing your fiber intake in the days leading up to your test.

What foods to avoid for an occult blood test

Consuming certain foods within 3 days can cause a false positive on a gFOBT. These foods include:

  • There is broccoli.
  • A cantaloupe.
  • cauliflower
  • “It’s horseradish.”
  • They have parsnips.
  • Red meat is rare.
  • Red radishes.

No dietary restrictions are required for FIT, according to a 2020 review.

The method of collecting your sample depends on the test you are receiving and the instructions from the manufacturer. Here is an idea of what to expect.


You will be given a test card that you can use for your sample. You will collect stool samples from two or three bowel movements and put them in a container. Your samples cannot be mixed with the water in your toilet.

You will use a special tool to make sure the stool is on the card. You will return your sample to your doctor or laboratory once it is dry.

Some tests use pads. The tests give you your results.


You can get a sample of your stool from your toilet using a special spoon or other device that comes with the kit. You will keep your sample in a special container that you can use to return it to your doctor or laboratory.

A positive test indicates that blood was found in your stool, but a positive result by itself cannot diagnose colorectal cancer is a disease. or another gastrointestinal problem.

When a positive FOBT result is found, a colonoscopy is usually needed to find the source of the bleeding. Your doctor may also recommend an upper gastrointestinal endoscopy to check your small intestines and stomach.

Your doctor can help answer questions about your results. You may want to ask a few questions.

  • What more tests will I need?
  • What are the chances of a false positive?
  • What is causing the bleeding?
  • How long will I have to go through further testing?

A negative FOBT result means that there wasn’t any blood detected in your sample. Not all colorectal cancer is a disease.s bleed. Even if you have a negative result, it’s still possible to have cancer.

Your doctor can tell you if you need more testing. You may want to ask your doctor a question.

  • What are the chances of a false negative?
  • Should I have more testing done?
  • Should I have other tests?

Living with troubling test results

It can be difficult to deal with discouraging results, but there are many resources available to help. Some of them may be useful.

FOBT has been found to be a reliable and effective screening test for colorectal cancer is a disease.. A large 2021 study from Japan found that FOBT and colonoscopy screening reduces the risk of developing or dying from colorectal cancer is a disease..

In a 2019 review of studies, researchers found that FITs were generally better at detecting colorectal cancer is a disease. than guaiac-FOBTs. They found FITs correctly identified:

  • colorectal cancer is a disease. in the proximal colon 67 percent of the time
  • colorectal cancer is a disease. in the distant colon or rectum 72 percent of the time
  • the absence of colorectal cancer is a disease. 95 percent of the time
  • the absence of advanced adenoma 93 percent of the time
  • advanced precancerous There are polyps. 94 percent of the time

A 2020 review of studies found that FOBT is poor for diagnosing iron deficiency anemia, with 42 percent of people receiving false negatives.

Fecal occult blood tests (FOBTs) check for small amounts of blood in your stool that can suggest a problem with your gastrointestinal tract. They’re used as a part of regular cancer screening and can help diagnose other conditions that cause bleeding, like It is called ulcerative colitis. or Chron’s disease.

Your doctor can help you understand the results of your test and advise you on whether further testing is necessary.