30th April 2024

A 45-year-old woman presents with a 2-day history of fever, right upper quadrant abdominal pain, and jaundice.

A 45-year-old woman presents with a 2-day history of fever, right upper quadrant abdominal pain, and jaundice. She has a history of gallstones and was previously healthy. On examination, she has a fever of 38.5°C, jaundice, and tenderness in the right upper quadrant of her abdomen. Her vital signs are otherwise stable. Laboratory investigations reveal a white blood cell count of 12.0 × 10⁹/L and raised serum bilirubin and alkaline phosphatase levels.

Which test would be the most appropriate initial investigation to confirm the most likely diagnosis?