This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pancreas, Subject name: Surgery
A 40-year-old man underwent laparoscopic cholecystectomy 2 years earlier. He remains asymptomatic until 1 week before admission, when he complains of RUQ pain and jaundice. He develops a fever and has several rigor attacks on the day of admission. An ultrasound confirms the presence of gallstones in the distal CBD. The patient is given antibiotics. Which of the following should be undertaken as the next step in therapy? 
Select and explain. 
A. Should be discharged home under observation, B. Should be observed in the hospital, C. Undergo surgical exploration of the CBD, D. ERCP with sphincterotomy and stone removal
D: ERCP with sphincterotomy and stone removal
Answer: D: ERCP with sphincterotomy and stone removal 
Explanation: The patient described has the features of Charcot's triad-jaundice, abdominal pain, and rigors, which indicates the presence of ascending cholangitis in a patient with obstructive jaundice. The patient should be treated with broad spectrum IV antibiotics and undergo ERCP, sphincterotomy, and stone extraction. If this fails, surgical exploration of the CBD will be required.