A 70-year-old woman with hypertension, atrial fibrillation, congestive heart failure, and gallstones presented to the emergency department with 3 days of nausea, vomiting, and abdominal pain. She reported no hematemesis, hematochezia, or melena and had no history of abdominal surgery. On admission to the emergency department, she was afebrile, her blood pressure was 80/60 mm Hg, and heart rate was 122/min. On physical examination, her abdomen was distended, tympanic, and slightly tender to palpation diffusely. Blood testing showed a white blood cell count of 10 450/μL (84.1% neutrophils); C-reactive protein level, 9.5 mg/dL; potassium level, 3.0 mEq/L (reference, 3.6-5.2 mEq/L); and creatinine level, 5.57 mg/dL (429.39 μmol/L, up from a baseline level of 0.80 mg/dL [70.72 μmol/L]). Sodium and liver function values were normal.