Stool guaiac test

Stool guaiac test is a noninvasive medical test used to detect the presence of occult blood in the stool. Occult blood refers to blood that cannot be seen without a microscope or chemical test. The test is also known as the guaiac fecal occult blood test (gFOBT).

Overview

The stool guaiac test is one of several methods used to detect occult blood in the stool. It is often used as part of a routine screening for colorectal cancer, especially in individuals over the age of 50. The test can also help diagnose other conditions that cause bleeding in the digestive tract, such as peptic ulcers, diverticulosis, and hemorrhoids.

Procedure

The stool guaiac test involves the collection of three separate stool samples, usually taken on different days. The samples are then applied to a special card, which is treated with a chemical derived from the guaiacum tree. When this chemical reacts with blood in the stool, it changes color, indicating a positive result.

Interpretation

A positive stool guaiac test indicates the presence of occult blood in the stool, but it does not reveal the source of the bleeding or the cause. Further diagnostic tests, such as a colonoscopy or upper endoscopy, may be needed to identify the cause of the bleeding.

Limitations

The stool guaiac test is not perfect and can produce false-positive or false-negative results. Certain foods and medications can interfere with the test results. In addition, the test may not detect all cases of colorectal cancer, as not all cancers or polyps bleed.

See also

• Fecal immunochemical test
• Colonoscopy
• Upper endoscopy

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