A 2-year-old patient with chronic abdominal pain presented with acutely worsening abdominal pain and acute anemia. The patient had no stigmata of bleeding including no hematemesis, melena or hematochezia, but had falling hemoglobin and hematocrit over the course of 24 hours. Abdominal ultrasound and computerized tomography showed a large cystic, fluid filled mass in the right midabdomen. The patient was taken to the operating room and a blood-filled mass arising from the ileum was identified and resected by the surgical team. Pathology was consistent with Meckel's diverticulum with heterotopic gastric mucosa. This is an atypical presentation of Meckel's diverticulum with bleeding contained within the diverticulum rather than bleeding in the intestinal lumen. Gastroenterologists must consider this unusual presentation when encountering progressive, acute anemia even in the absence of overt gastrointestinal blood loss.