To compare the technique of combined balloon sphincter dilation after an initial sphincterotomy and standard sphincterotomy in the endoscopic removal of large bile duct stones. The investigators hypothesize that combined balloon dilation and sphincterotomy allows for easier stone removal without added morbidities when compared to standard sphincterotomy.

Endoscopic sphincterotomy is a standard technique to enlarge the bile duct opening before stone removal during endoscopic retrograde cholangiopancreatography. However, complete sphincter ablation by endoscopic sphincterotomy is not always possible. Also, due to the tapering end of the distal duct, standard sphincterotomy may not be adequate for removal of particularly large stones. In a retrospective series by Ersoz et al, the addition of balloon dilation after sphincterotomy achieves a high stone clearance rate (89-95%). The investigators postulate that the combination of endoscopic sphincterotomy followed by balloon dilation may allow easier stone retrieval with acceptable complication rate.

Inclusion Criteria:

• Patients at least 18 years old, presented to Prince of Wales Hospital for endoscopic retrograde cholangiopancreatography (ERCP) for known or suspected bile duct stones are invited to participate.
• Informed consent will be obtained before the beginning of ERCP.
• Patients are randomized to EST or ESBD after confirming the presence of bile duct stones on the initial cholangiogram

Exclusion Criteria:

• septic shock, coagulopathy (international normalized ratio >1.3,
• partial thromboplastin time greater than twice that of control),
• platelet count <50,000x103/uL or
• ampullary tumors