Patients with ulcerative colitis have an increased risk for developing biliary diseases, including primary sclerosing cholangitis and cholangiocarcinoma. A duodenal ulcer would be characterized by abdominal pain and melena. Tumor bleeding from a cholangiocarcinoma would most likely present as iron deficiency anemia, melena, or, rarely, hematemesis. Hemorrhoids would present as bright red blood without diarrhea. Shigella enteritis could cause bloody diarrhea but would neither be intermittent nor last several years.