the specification discloses a fecal occult blood test device capable of determining whether the blood found during the test originated in the upper or lower gastrointestinal track . a fecal sample is applied to a test medium charged to be differentially attractive to blood components originating in the upper and lower gastrointestinal track respectively . a solvent is applied to the test specimen to cause differential migration of the blood components and an indicator is then applied to indicate the presence of the blood components , if any .