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Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
A 33-year-old woman presents with black stools. Laboratory studies demonstrate a hypochromic, microcytic anemia. Upper GI endoscopy reveals a duodenal ulcer. Which of the following best describes the stools in this patient with peptic ulcer disease?
assistant
The correct answer is  Melena (black stool) is a symptom of upper gastrointestinal bleeding. Blood from ruptured esophageal varices or a peptic ulcer is partially digested by hydrochloric acid. Hemoglobin is transformed into a black pigment (hematin), which imparts a typical "coffee-grounds" color to the stool. Hematemesis (choice A) is vomiting of blood. Hematobilia (choice B) is bleeding into the biliary passages, as a complication of trauma or neoplasia. Hematochezia (choice C) is passage of bloody stools caused by lower gastrointestinal hemorrhage. Steatorrhea (choice E) is passage of fatty stools caused by pancreatic disease and malabsorption.Diagnosis: Peptic ulcer disease