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Intestinal Bleeding
Gastrointestinal (GI) bleeding is acute or chronic loss of blood from the upper or lower part GI tract ( Fig. 82.1 ). Acute bleeding may be life threatening, whereas chronic bleeding may be slow or even occult. The GI tract can lose as much as 50 mL of blood daily; it is replaced without anemia but indicates a GI lesion. This chapter discusses lower GI bleeding; Chapter 35 discusses upper GI hemorrhage (see also Section IV ).
Gastrointestinal Hemorrhage: Causes and Manifestations.
Lower GI bleeding can be defined as blood loss from below the ligament of Treitz. It accounts for approximately one-fourth to one-third of all bleeding events. The incidence appears to increase with age, with more than a 200-fold increase from the third to the ninth decades of life, and it is more common in men than in women. The mortality rate is less than 5%. Upper GI bleeding has a higher mortality rate than lower GI bleeding.
Clinical Picture
If a patient has anemia, it is important to examine his or her stool for occult blood. If findings are positive, the GI tract must be ruled out as the probable cause of the anemia. After the upper GI tract is ruled out, the intestine must be investigated. Severe hemorrhages reveal themselves by the appearance of visible blood in the stool. Such blood may be bright red, or it may cause melena, a black discoloration, indicating that the blood has been exposed to digestive activity and usually that the bleeding stems from above the ligament of Treitz. Often, however, melena may be from the small bowel or from as far down as the cecum. Red blood in the stool results from severe bleeding. It is important not to be fooled by a black stool caused by the ingestion of iron supplements, bismuth preparations, or foods such as blackberries. Furthermore, red beets, when consumed in large amounts, can produce a red stool.
Patients with occult bleeding usually have few GI symptoms. However, when the symptoms point to the upper GI tract, that workup precedes the lower GI workup. Some patients who are severely anemic may be weak, which usually signifies that occult bleeding has existed for a long time. Acute rectal bleeding that presents as hematochezia (blood in feces) and bright-red blood may start with a bout of syncope or as a blood-filled toilet bowl. Patients with acute rectal bleeding must be monitored immediately.
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