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: Surgery
Treatment of retained CBD stone is? 
Select and explain. 
A. Endoscopic Sphincterotomy, B. Laparoscopic CBD exploration, C. Percutaneous stone extraction, D. ESWL
A: Endoscopic Sphincterotomy
Answer: A: Endoscopic Sphincterotomy 
Explanation: Endoscopic Sphincterotomy REF: Maingot's 10th e p. 1746 Retained stone: stones diagnosed sholy after cholecystectomy Recurrent stone: diagnosed months or years after Treatment of retained stones: Found on T tube cholangiogram Removal of stones radiologically after maturation of T tube tract after 4 weeks Treatment of recurrent CBD stones Endoscopic sphincterotomy is treatment of choice since T tube is not present after 4 weeks In unsuccessful cases ESWL has proven beneficial