Obstructive Jaundice — Surgical Workup

A 58-year-old man presents with painless progressive jaundice, pale stools, and dark urine for 3 weeks. Ultrasound shows dilated intrahepatic and extrahepatic bile ducts with a dilated pancreatic duct. Which single clinical or investigative finding best distinguishes pancreatic head carcinoma from choledocholithiasis in this patient?

A 52-year-old woman with a history of recurrent cholecystitis presents with obstructive jaundice. Imaging shows dilated intrahepatic bile ducts and a normal-sized gallbladder. Which investigative finding best distinguishes primary sclerosing cholangitis (PSC) from extrahepatic bile duct obstruction due to malignancy?

Which laboratory finding is most specific for distinguishing obstructive (post-hepatic) jaundice from hepatocellular (hepatic) jaundice?

A 58-year-old man from Delhi presents with progressive jaundice for 3 weeks, pale stools, and dark urine. On examination, he has a palpable gallbladder and no hepatomegaly. Serum bilirubin is 8.2 mg/dL (direct 6.8 mg/dL), ALP 280 IU/L, ALT 95 IU/L. Ultrasound abdomen shows dilated intrahepatic bile ducts, dilated common bile duct (12 mm), and a normal gallbladder with no stones. What is the most appropriate next step in management?

A 62-year-old woman with a history of recurrent cholangitis presents with fever (38.5°C), right upper quadrant pain, and jaundice. Laboratory tests show bilirubin 7.4 mg/dL, alkaline phosphatase 380 IU/L, and WBC 14,200/μL. Abdominal ultrasound reveals dilated intrahepatic bile ducts with multiple echogenic foci within the ducts, a normal-caliber common bile duct, and a normal gallbladder. What is the most likely diagnosis, and what is the immediate management priority?