Guaiac cards and bottle of developer.

A stool guaiac test detects the presence of fecal occult blood. Fecal occult blood is a term for blood present in the feces that is not visibly apparent. ...

It involves feces, a thick piece of paper attached to a thin film coated with guaiac (which comes from a plant), and hydrogen peroxide. Either the patient or medical professional smears a small fecal sample onto the film, drips one or two drops of peroxide on the film, and observes for a color change. Feces, faeces, or fæces (see spelling differences) is waste product from an animals digestive tract expelled through the anus (or cloaca) during defecation. ...

The fecal sample can be obtained either by wiping soiled toilet tissue on the film. In medical settings, it's obtained either with a gloved finger (with a digital rectal exam) or with a wooden stick dipped into stool. Only a small sample for smearing is necessary; a mound of stool would actually impede an accurate test. A rectal examination or rectal exam is an internal examination of the rectum by a physician. ...

When peroxide (a liquid) is dripped onto the guaiac, it oxidizes the guaiac causing a color change. This oxidation occurs very slowly. Heme, a component of hemoglobin found in blood, catalyzes this reaction, giving a result in about 2 seconds. Therefore, a positive test result is one where there is a quick color change of the film. Peroxide has three distinct meanings: // Main article: hydrogen peroxide In common usage, peroxide is an aqueous solution of hydrogen peroxide (HOOH or H2O2) sold for use as a disinfectant or mild bleach. ...

External Links

• Medline Plus: stool guaiac test. National Institute of Health. Retrieved on 2007-01-05.