[Prevention of false results in tests for occult blood in feces].

The HaemoQuant test and the immunological tests are not devoid of problems so that the (pseudo)peroxidase-sensitive tests are anything but obsolete. Most of the tests are nowadays sold with reduced sensitivity, with the risk of false-negative results. Nevertheless, they can yield false-positive results without a strict dairy-and-vegetable diet in which all components have undergone a heat inactivation (cooking, baking, pasteurization). Uncooked wheat bran reacts strongly, but even liberal use of cooked bran never produced a positive reaction with the sensitive 'Occultest'. Even if thoroughly cooked, all meat, except that of fish with white meat, can elicit a positive reaction. Most leaflets of commercial tests should be thoroughly revised. Also a misleading presentation of a positive reaction can be a source of errors.