This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
[{'content': 'A 56 year old man presents to his internist with jaundice. The patient is receiving no medication and his only symptomatic complaints is mild fatigue over the past 2 months. Physical examination is remarkable only for the presence of scleral icterus. The patient has no significant past medical history. Analysis of serum chemistry reveals the following: SGOT : 0.58 microkat/L (35U/L) SGPT : 0.58 microkat/L (35U/L) Total bilirubin : 91.7 micron mol/L (7 mg/dL) Direct Bilirubin : 85.5 micron mol/L (5mg/dL) Alkaline phosphatase:12 micron kat/L (720U/L) Which of the following is the next appropriate diagnostic step? \nSelect and explain. \nA. Ultrasound, B. Liver biopsy, C. Review of peripheral blood smear, D. Endoscopicretrograde cholangiopancreatography (ERCP)', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Answer is A (Ultrasound): Initial investigation of choice in a case of obstructive jaundice is: ULTRASONOGRAPHY The patient in question has an obstructive form of jaundice, as is indicated by marked elevation of conjugated hiliruhin together with a significant rise is Alkaline phosphatase. Patient: should therefore be next subjected to ultrasonography to confirm the diagnosis and if possible locate the site of block.', 'role': 'assistant'}]