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Fecal Occult Blood Test

This Non-Invasive Test Can Help Determine If There Is Blood In Your Stool

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Updated March 21, 2014

What Is It?

A fecal occult blood test (also called stool guaiac or hemoccult test) is used to examine stool for traces of blood that can not be seen with the naked eye. This test can detect bleeding from almost anywhere in the digestive tract, and can come out positive in the presence of one of several conditions, including colorectal cancer, esophagitis, gastritis, stomach cancer, ulcerative colitis and hemorrhoids. It can also be positive when asprin or other medications that irritate the digestive tract have been used.

What Is It Used For?

A fecal occult blood test is often used to dectect colorectal cancer in its early stages, which has no other signs or symptoms. Fecal occult blood tests are usually recommended annually for people over 50 years old. People at high risk for colorectal cancer because of family history or polyps should begin testing at age 40.

What Is The Preparation?

You should not test if you:

  • Have active bleeding from a hemorrhoid or anal fissure
  • Have blood in your urine
  • Have taken asprin or other nonsteroidal anti-inflammatory drugs (NSAIDs) in the past 7 days
  • Are a woman having your menstral period or during the first three days after the end of your period

At least 72 hours before the test, the following dietary changes should be made:

  • Avoid taking more than 250 mg/day of vitamin C
  • Avoid eating red meat (beef or lamb), including liver and processed meats or "cold cuts"
  • Avoid eating raw fruits and vegetables, especially melons, radishes, turnips, and horseradish

Any toilet bowel cleansers should be removed from the toilet, as they can affect the results of the test.

How Is It Done?

You will be given a kit to be used for collecting stool samples for the test. This kit should be kept in the bathroom at home, or carried with you when you're away from home during the three day test. Be sure to write your name and other information on the collection slides.

Flush the toilet twice before a bowel movement. Use one of the small wooden sticks from the kit to collect a sample of stool. Apply the sample to the correct space on the sampling slide. Repeat for two more days or two more bowel movements as directed by your doctor. Cover the slides and store them away from heat, light, and strong chemicals.

After completing the test, seal the test envelope and return the kit to your doctor or the laboratory.

What Are The Risks?

This test is safe and painless.

Is A Follow-up Necessary?

Call your doctor in a few days for the results. With a positive test, additional procedures such as a sigmoidoscopy or a colonoscopy may be recommended.

When Should I Call The Doctor?

If you have diarrhea or constipation during the test period.

Anything Else I Should Know?

Read all instructions carefully before testing begins.

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