a hidden source for upper gastrointestinal bleeding

a 50-year-old lady presented with bloody vomiting and melena since four days prior to admission. her medical history was significant only for hypertension which was controlled by a 5 mg daily dose of amlodipine. she occasionally took nsaids. on admission, the physical exam revealed only mild tachycardia and pallor. hemoglobin was 9.7 g/dl, which subsequently declined to 7.9 g/dl. the first upper gastrointestinal (gi) endoscopy was remarkable for a paraesophageal hiatal hernia, with no site of bleeding detected. the second upper gi endoscopy did not find any source for bleeding. a third endoscopic examination revealed a new finding (figures a and b).