Bleed Identified, Infection Ruled Out: What Next?

A previously healthy 45-year-old man presents with melena of several day’s duration. On review of symptoms, he reports fatigue and light-headedness while standing. Results of laboratory studies reveal a hemoglobin level of 8 g/dL. He undergoes upper endoscopy, which demonstrates a 6-mm clean based ulcer in the duodenum without stigmata of bleeding. Tissue biopsies are taken to rule out Helicobacter pylori.