DefinitionThe stool guaiac test finds hidden (occult) blood in the stool (bowel movement). 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 smearHow the test is performedIf the test is performed in an office or hospital, stool may be collected by a doctor during an examination.If the test is performed at home, a stool sample from three consecutive bowel movements is collected, smeared on a card, and mailed to a laboratory for processing. In order to ensure the accuracy of the guaiac test, follow the manufacturer's instructions on how to collect the stool.There are many ways to collect the samples. You can catch the stool on plastic wrap that is loosely place