black tarry stools containing digested blood

However, quantity can be difficult to assess because even small amounts (5 to 10 mL) of blood turn water in a toilet bowl an opaque red, and modest amounts of vomited blood appear huge to an anxious patient.

History of present illness should attempt to ascertain quantity and frequency of blood passage. GI bleeding in patients with underlying liver disease may precipitate portosystemic encephalopathy or hepatorenal syndrome (kidney failure secondary to liver failure). Patients with underlying ischemic heart disease may develop angina or myocardial infarction because of coronary hypoperfusion.

Patients may present with signs of shock. Black stool that does not contain occult blood may result from ingestion of iron, bismuth, or various foods and should not be mistaken for melena.Ĭhronic occult bleeding can occur from anywhere in the GI tract and is detectable by chemical testing of a stool specimen.Īcute, severe bleeding also can occur from anywhere in the GI tract. About 100 to 200 mL of blood in the upper GI tract is required to cause melena, which may persist for several days after bleeding has ceased. Melena is black, tarry stool and typically indicates upper GI bleeding, but bleeding from a source in the small bowel or right colon may also be the cause. Hematochezia is the passage of gross blood from the rectum and usually indicates lower GI bleeding but may result from vigorous upper GI bleeding with rapid transit of blood through the intestines. It results from upper GI bleeding that has slowed or stopped, with conversion of red hemoglobin to brown hematin by gastric acid. Coffee-ground emesis is vomiting of dark brown, granular material that resembles coffee grounds. Hematemesis is vomiting of red blood and indicates upper GI bleeding, usually from a peptic ulcer, vascular lesion, or varix. (See also Varices and Vascular Gastrointestinal Lesions. The manifestations depend on the location and rate of bleeding. Gastrointestinal (GI) bleeding can originate anywhere from the mouth to the anus and can be overt or occult.

Black tarry stools containing digested blood