A 27-year-old woman was admitted on an emergency basis, with acute pain in the right upper abdominal quadrant and nausea and vomiting for the previous 3 days. Her medical history was normal. On physical examination, she was dehydrated, with a positive Murphy sign and mild fever. Blood cell count was normal. Results of blood chemistry demonstrated a mild hyperbilirubinemia (total bilirubin level: 1.8 mg/dL and direct bilirubin level: 1.6 mg/dL [to convert both to micromoles per liter, multiply by 17.104]) and mildly elevated alkaline phosphatase (150 U/L [to convert to microkatals per liter, multiply by 0.0167]) and γ-glutaminotranspeptidase (105 U/L) levels.