Stool guaiac

Alternative names:

stool occult blood (OB) test

How the test is performed:

Adults and children:
There are many ways to collect the samples. You can catch the stool on plastic wrap that is loosely placed over the toilet bowl and held in place by the toilet seat. Then put the sample in a clean container. One test kit supplies a special toilet tissue that you use to collect the sample, then put the sample in a clean container.

Infants and young children:
For children wearing diapers, you can line the diaper with plastic wrap. If the plastic wrap is positioned properly, isolating the stool from any urine output, mixing of urine and stool can be prevented for a better sample.

Laboratory procedures may vary. In one type of test, a small sample of the stool is placed on a special paper "card". A drop or two of testing solution is applied to the opposite side of the card. A color change indicates the presence of blood in the stool.

How to prepare for the test:

Do not consume red meat for 3 days.
Discontinue drugs that can interfere with the test (see "special considerations").

How the test will feel:

This test involves only normal bowel functions, and there is no discomfort.

Why the test is performed:

This test is a screening test to detect blood in the gastrointestinal tract.

Normally, only minute amounts of occult blood are passed into the gastrointestinal (GI) tract, that is not enough to be picked up by the standard tests such as the guaiac test.