Gastroenterology and Hepatologymiddle twist
A 34-year-old man with established primary sclerosing cholangitis develops worsening pruritus and jaundice over six weeks, with a 5 kg weight loss. His bilirubin has risen from 34 to 146 micromol/L (3–20), and imaging shows a new dominant hilar stricture. Brush cytology obtained at endoscopic retrograde cholangiopancreatography is negative for malignant cells. Which one of the following is the most appropriate next investigation?