Black and Bloody Stools - Melena and Hematochezia Melena - Refers to passage of black, tarry (sticky and shiny) stools. Occult blood tests are positive. Involves loss of at least 60 mL of blood into the gastrointestinal tract (less in children), usually from the esophagus, stomach, or duodenum and transit time of 7—14 hours. Less commonly, when transit is slow, blood loss originates in the jejunum, ileum, or ascending colon. In infants, melena may result from swallowing blood during the birth. Black, Nonsticky Stools - May result from other causes, with negative occult blood tests. These stools have no pathologic significance. Red Blood in the Stools (hematochezia) - Usually originates in the colon, rectum, or anus; much less frequently from the jejunum or ileum. Upper gastrointestinal hemorrhage may also cause red stools; blood loss is then usually large (more than a liter). Rapid transit through the intestinal tract leaves insufficient time for the blood to turn black from oxidation of iron in hemoglobin. #Melena #Hematochezia #Diagnosis #Differential #Causes #GIBleed
