what is a positive stool exam for occult blood significant for
Fecal occult blood Fecal occult blood testing (FOBT), as its name implies, aims to detect subtle blood loss in the gastrointestinal tract, anywhere from the mouth to the colon. Positive tests ("positive stool") may result from either upper gastrointestinal bleeding or lower gastrointestinal bleeding and warrant further investigation for peptic ulcers or a malignancy (such as colorectal cancer or gastric cancer). The test does not directly detect colon cancer but is often used in clinical screening for that disease, but it can also be used to look for active occult blood loss in anemia[2] or when there are gastrointestinal symptoms.[3]
Pregnancy test A pregnancy test attempts to determine whether a woman is pregnant. Markers that indicate are found in urine and blood, and pregnancy tests require sampling one of these substances. The first of these markers to be discovered, human chorionic gonadotropin (hCG), was discovered in 1930 to be produced by the syncytiotrophoblast cells of the fertilised ova (eggs). While hCG is a reliable marker of pregnancy, it cannot be detected until after implantation:[1] this results in false negatives if the test is performed during the very early stages of pregnancy. HCG can be detected via blood 8 days after fertilization of the egg, and in the urine 10 days after. Obstetric ultrasonography may also be used to detect pregnancy. Obstetric ultrasonography was first practiced in the 1960s; the first home test kit for hCG was invented in 1968.[2] The kits went on the market in the United States and Europe in the mid-1970s.