Fecal Occult Blood Rapid Test Cassette (Feces) is a rapid test to qualitatively detect low levels of fecal occult blood in feces. Collect a random sample of feces in a clean, dry receptacle. The test uses double antibod- sandwich assay to selectively detect as low as 50 ng/mL of hemoglobin or 6 μg hemoglobin/g feces.