Feces Collection:
Small aliquots of feces are frequently analyzed to detect the presence of "hidden" blood, so called occult blood, which is recognized as one of the most effective clues to the presence of bleeding ulcer or malignant disease in the gastrointestinal tract.
Feces from children may be screened for trypic activity to detect cystic fibrosis. Fecal material for these test are usually recovered from the infant's diaper.
In adults, measurement of fecal nitrogen and fat in 72 hr specimen is used to assess the severity of malabsorption; measurement of fecal porphyrins is occasionally required to characterize the type of porphyria.