A 23-year-old otherwise healthy man presented to the emergency department after a 3-hour flight with complaints of headache and severe abdominal pain. His symptoms followed a 1-day discharge from a recent hospital admission for a viral illness. He denied any history of trauma, and the remaining medical history was unremarkable. At the time of evaluation, he reported associated left shoulder pain and was in noticeable distress. Physical examination revealed a distended abdomen with associated diffused peritoneal signs. He was afebrile, with a heart rate of 77 beats/min, blood pressure of 96/46 mm Hg, oxygen saturation of 100% in room air, and a respiratory rate of 16 breaths/min. Abdominal ultrasonography was performed (Figure 1).