ABSTRACT
Acute lower gastrointestinal tract bleeding is defined as the recent onset of gross gastrointestinal bleeding from a site distal to the ligament of Treitz. Severe acute lower gastrointestinal tract bleeding is associated with unstable vital signs, rapidly developing anemia, and/or a need for transfusion. Operationally, this definition is equivalent to voluminous hematochezia (gross red rectal bleeding), although it does not exclude melena (black stools due to gastrointestinal bleeding). The source is not usually apparent on clinical grounds, making for an overlap with acute upper gastrointestinal tract bleeding until endoscopic or radiographic studies define the site of blood loss with more precision (1-6). Approximately 10% to 15% of patients presenting with voluminous hematochezia have a source in the upper gastrointestinal tract. Relatively few disorders typically present with severe acute lower gastrointestinal tract bleeding. Many more lesions in the lower gastrointestinal tract produce lesser degrees of bleeding, although most occasionally can produce voluminous hemorrhage. This chapter focuses on the diagnosis and management of severe acute lower gastrointestinal tract bleeding.
