A 70-year-old woman complains of several hours of lower abdominal cramping and massive rectal bleeding. Nasogastric aspirate shows bile but no blood. Her most likely diagnosis is:
Peptic ulcer disease.
The most common cause of apparent massive lower gastrointestinal bleeding (LGIB) remains upper gastrointestinal bleeding, which must be excluded in all patients. The most common cause of documented LGIB in the elderly is diverticulosis, although angiodysplasia, especially of the right colon, is also a common etiology. Hemorrhoids are the most common cause of rectal bleeding but rarely cause massive blood loss. Ischemic colitis usually does not result in massive bleeding. Colon carcinoma is usually manifested by occult blood.