A 45-year-old woman presents to the emergency department with severe right upper quadrant pain, nausea, and vomiting that started eight hours ago after eating a fatty meal. She has a history of gallstones but has not sought treatment. On physical exam, she has scleral icterus and a positive Murphy’s sign. Vital signs are normal. Laboratory tests reveal the following: •White blood cells (WBC): 11,500/uL (normal: 4,500-11,000/uL) •Hemoglobin (Hgb): 13.0 g/dL (normal: 12.1-15.1 g/dL) •Platelets (PLT): 380,000/uL (normal: 150,000-450,000/uL) •Alanine aminotransferase (ALT): 210 U/L (normal: 7-56 U/L) •Aspartate aminotransferase (AST): 190 U/L (normal: 8-33 U/L) •Total bilirubin (T Bili): 3.5 mg/dL (normal: 0.1-1.2 mg/dL) •Alkaline phosphatase: 80 U/L (normal: 44-147 U/L) •Gamma-Glutamyl Transpeptidase (GGT): 60 U/L (normal: 5-40 U/L) •Lipase: 90 U/L (normal: 10-140 U/L) •Amylase: 70 U/L (normal: 40-140 U/L).What is the most likely location of the biliary obstruction in this patient?
