occult blood test

occult blood test

Etymology: L, occultare, to hide; AS, blod + L, testum, crucible

a test for the presence of microscopic amounts of blood in the feces secondary to bleeding in the digestive tract. The minimal amounts of occult blood normally passed into the GI tract are not usually significant enough to cause a positive result for occult blood testing. Benign and malignant GI tumors, ulcers, inflammatory bowel disease, arteriovenous malformations, diverticulosis, and hematobilia can cause the appearance of occult blood in the stool, as can swallowed blood from oral or nasal pharyngeal bleeding.

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occult

obscure or hidden from view.

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occult blood test

examination, microscopically or by a chemical test, of a specimen of feces, urine, gastric juice, etc., to determine the presence of blood not otherwise detectable. Feces are tested when intestinal bleeding is suspected but there is no visible evidence of blood in the stools.

occult heartworm infection

infection by Dirofilaria immitis in which circulating microfilariae cannot be detected in the peripheral blood by the usual test methods.

occult spavin

see occult spavin.

occult virus

the virus or infectious agent cannot be isolated but there is strong circumstantial evidence that it is present, e.g. scrapie prion.