Faecal occult blood

Under physiological conditions, very small amounts of blood are excreted with stool daily. Greater than physiological amounts of blood may appear in the stool in case of some gastrointestinal diseases. The stool occult blood test detects human hemoglobin (a blood component) using immunochromatographic tests in a stool sample. It is used in diagnosing gastrointestinal diseases, especially bleeding from various sections. It is a screening test for colorectal cancer and is also used in diagnosing anemia to determine the cause of iron deficiency. It should be performed preventively every year in people over 50 years old. A positive result indicates the presence of blood in the tested stool sample. In such a case, further diagnostics are necessary to determine the cause of the bleeding. A positive result may occur in patients with colorectal cancer, polyposis, inflammatory diseases (Crohn’s disease, ulcerative colitis), stomach/duodenal ulcers, food intolerances, or hemorrhoids. A false positive result may occur in cases of gum or nose bleeding when blood enters the digestive tract, constipation with bleeding, use of blood-thinning medications, and in women, also menstruation. In some patients, stool samples from several bowel movements (usually three) are tested to avoid false negative results. A negative result, however, does not exclude disease – it only confirms the absence of blood in the tested stool sample.