The stool guaiac test finds hidden (occult) blood in the stool (bowel movement), even when you cannot see the blood yourself.
It is the most common form of fecal occult blood test (FOBT) in use today.
Alternative NamesGuaiac smear test; Fecal occult blood test - guaiac smear; Stool occult blood test - guaiac smear
How the test is performedIn the most common way of doing a stool guaiac test, a small sample of stool is placed on a paper card and a drop or two of testing solution is added. A color change is a sign of blood in the stool.
If the test is performed in an office or hospital, a doctor may collect a small amount of stool during a rectal examination.
If the test is performed at home:
There are many ways to collect the samples:
Do not take stool samples from the toilet bowl water, because this can cause errors.
For infants and young children wearing diapers, you can line the diaper with plastic wrap. Place the plastic wrap so that it keeps the stool away from any urine. Mixing of urine and stool can spoil the sample.
To make sure the guaiac test is accurate, follow the manufacturer's instructions on how to collect the stool.
How to prepare for the testDo not eat red meat, cantaloupe, uncooked broccoli, turnip, radish, or horseradish for 3 days before the test. These foods can sometimes interfere with the test.
You may need to stop taking medicines that can interfere with the test. These include vitamin C, aspirin, and nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen and naproxen.
Check with your health care provider about medication changes you may need to make. Never stop or decrease any medication without first talking to your health care provider.
How the test will feelThere is no discomfort when the test is done at home, because this test only involves a normal bowel movement. If stool is collected during an exam, there may be some discomfort in the anal canal and rectum.
Why the test is performedThis test detects blood in the digestive tract for the following reasons:
A negative test result means that there is no blood in the stool.
What abnormal results meanAbnormal results may be caused by anything that causes bleeding in the stomach or intestinal tract, including:
Other causes of positive guaiac test may include:
Abnormal tests require follow-up with your doctor. In many cases, however, no explanation for the abnormal result is found.
What the risks areThere can be false-positive and false-negative results. Using the right collection technique, avoiding certain drugs, and observing food restrictions can reduce errors.
ReferencesTack J. Dyspepsia. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 9th ed. Philadelphia, Pa: Saunders Elsevier; 2010:chap 13.
Reviewed ByReview Date: 01/14/2012
Neil K. Kaneshiro, MD, MHA, Clinical Assistant Professor of Pediatrics, University of Washington School of Medicine. David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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A positive guaiac test indicates the presence of blood in the stool, which can be an indicator of various gastrointestinal conditions such as ulcers, hemorrhoids, or colorectal cancer. Further evaluation is needed to determine the cause of the blood in the stool.
Stool guaiac is a diagnostic test used to detect the presence of hidden (occult) blood in a person's stool, which can indicate gastrointestinal bleeding. The test involves applying a small sample of stool to a guaiac-based reagent, which changes color in the presence of hemoglobin. It is commonly used as a screening tool for conditions such as colorectal cancer or gastrointestinal disorders. A positive result typically requires further investigation to determine the source of the bleeding.
The guaiac test is a medical screening tool used to detect hidden (occult) blood in stool samples, which can indicate gastrointestinal bleeding. The test involves applying a stool sample to a special card containing guaiac resin, which changes color in the presence of hemoglobin. It is commonly used to help diagnose conditions such as colorectal cancer, ulcers, and other digestive disorders. Although it is a useful screening method, it may require follow-up testing for definitive diagnosis.
It's great that there's no blood in your stool, but many patients can have colon cancer or precancerous colon lesions without having a positive guaiac test. Because so many cases are missed by the test for hidden blood in the stool, colonoscopy makes sense.
Guaiac-positive discharge means that there was blood in the discharge. This test may be used for breast discharge.
At home, after having a bowel movement, the patient is asked to swipe a sample of stool obtained with a small stick on a card. After three such specimens are on the card, the card is then easily chemically tested for occult blood also.
GWAY-ak refers to a type of antibody that can be tested for in the stool to detect gastrointestinal infections caused by certain bacteria like Campylobacter jejuni. A positive result indicates the presence of antibodies against this bacteria in the stool sample, suggesting an active infection that may be causing gastrointestinal symptoms. Further evaluation and treatment may be needed based on these test results.
Detect occult Blood in fecal matter.
The stool O and P test is the stool ova and parasites test. In this test, a stool sample is examined for the presence of intestinal parasites and their eggs, which are called ova.
They test stool for a lot of things, but drugs, so far as I know, are not one of the things they test it for. (Mostly stool samples are tested for bacteria and blood.) To test stool for drugs they'd have to liquify it, for starters. It would just be easier to ask for urine instead of stool.
This is a test whereby a very small stool smaple is smeared on the center film of a little square card - and then turned in to the lab to check for microscopic traces of blood. It is a screening test for colon cancer. There are many false positives (eating certain foods will turn the test positive). Therefore a positive test just means that the next step should be taken - such as a repeat test or even a colonoscopy, if indicated by your physician.