What are the causes of false negative results in stool blood testing?

Bogus Testing. To be falsely negative would imply the presence of blood that has been missed. Such an event commonly occurs with either a defective card, expired solution or poor sample. Try using a different card and solution. If there is a high suspicion of blood based on appearance or risk factors, a stool cell count can be done, a reagent test dropped into toilet water after defecating or fecal dna test.

Related Questions

Is a false positive result in stool blood testing possible?

Yes. Occult blood tests based on testing for peroxidase activity generate false positives from eating meat, horse radish and iron intake. Read more...
Certainly. If you take an iron supplement, it will turn a stool test positive, as that is what the stool test is for. Read more...

What is the ez detect stool blood testing kit?

Limited usefulness. This is a home kit to detect blood in stool. However, except for its convenience there is no advantage as it is a lesser sensitive assay compared to current state of art technology "fecal immunochemical testing" for blood. I am aware of only limited comparative data and it is not very supportive of ezd being comparable to clinical testing. Read more...
Colon cancer screen. Tests for blood in the stool which can indicate a problem such as polyps or colon cancer. Read more...

If I don't see a reaction when I use a stool blood test card, how can tell if the test is negative or if it's defective?

View control results. Most occult stool blood tests have a control spot on the paper that turns color (usually blue) . If the control turns color but the stool sample under the paper does not then your test is negative. If the control spot does not turn color then your test paper or solution is not working properly. Read more...
Ask your physician. After you collect the sample, you must send it back to your physician. There is a solution that is placed on the back of the card to make the color change happen. A small blue circle (control) will appear at the bottom of the test area. If this is the only color change present on the card, the test is negative and valid. Read more...

What could cause a positive iFOBT (stool blood) test in a young 23 yr old male? And is it serious? Doc referred me to GI

Many things! I'm assuming your doc ordered the test for a symptom, or anemia work up. If so, could be stomach ulcer, ulcer anywhere along gut, to bleeding diverticula in colon or even a hemmoroid. Also, vitamin with iron, nosebleed (because swallowed blood) or anything where blood gets into GI tract. Older tests would also turn positive if you had eaten red meat or spinach due to iron. Hope that helps! Read more...
True or false +'s... ...are possible. Whether blood is ingested, or originates in your gut, an occult blood test may be positive. Consider stopping any aspirin or NSAID use now (unless prescribed), and keep your GI appointment please. Read more...