Fecal Occult Blood Test (FOBT)

FOBT (Fecal Occult Blood Test)

How It Is Done

There are different home tests for fecal occult blood. It is important to follow the manufacturer's instructions provided with any test. For most tests, you will use stool samples from three different bowel movements over three different days.

General instructions

For any home test, follow these general guidelines:

• Check the expiration date on the package. Do not use a test kit after its expiration date. The chemicals in the kit may not work properly after that date.
• Store the test kit as instructed. Many kits need to be stored in a refrigerator or cool place.
• Read the instructions that come with your test carefully and completely before doing the test. Pay attention to any special preparations you need to take before doing the test, such as not eating certain foods or limiting your physical activity.
• Follow the instructions exactly. Do all the steps, in order, without skipping any of them.
• If a step in the test needs to be timed, use a watch. Do not guess at the timing.
• If you are color-blind or have trouble seeing colors, have someone else read the test results for you. Most test results are color changes on a test strip.
• Record the results of the test so you can discuss them with your health professional.

The following instructions are for one of the most common tests used to find blood in the stool.

Stool guaiac cards

• Complete the identification information on the front of each card.
• During a bowel movement, collect a small amount of stool on one end of an applicator. You might try catching the stool on some plastic wrap draped loosely over the toilet bowl and held in place by the toilet seat. If you use a container to collect the stool, first clean and rinse it well to get rid of any substance that may affect the test results.
• Apply a thin smear of stool inside box A.
• Reuse the same applicator to obtain a second sample from a different part of the stool. Apply a thin smear inside box B.
• Close the cover of the slide.
• Complete the remaining two cards in the same way for two other bowel movements.
• You probably will be instructed to return all slides to your health professional either in person or by mail within 4 days of collecting the samples.
• If your test kit has the developer solution, wait 3 to 5 minutes before you put 1 drop of the developer solution to the area with the stool. Put 1 drop of the developer solution to the control areas of the card so that you will know what positive and negative test results should look like. An area to read the results is found on the reverse side of the card. Turn the card over and read the results within 10 seconds.

Other test kits

• Some kits instruct you to use a special cloth to wipe with after a bowel movement. After wiping with the cloth, you put the developer solution on it to check for color change that means there is blood in the stool.
• Other kits have a special test pad that you place in the toilet after having a bowel movement. The pad will change color if the stool has blood in it.

If you find blood in your stool, call your health professional as soon as possible.

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Author:	Monica Rhodes	Last Updated: August 11, 2008
Medical Review:	Kathleen Romito, MD - Family Medicine Peter J. Kahrilas, MD - Gastroenterology
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