Limited endoscopic sphincterotomy with balloon dilation（ESBD）is a promising technique in treating common bile duct stones. It had the similar success rate of stone extraction, but its incidence of complications remained uncertain. However, there is no clinical evidence and guideline to define the optimal duration of balloon dilation so far. So we designed a prospective randomized trial to compare the effect of three different duration of balloon dilation during ESBD so that we can find the optimal duration of the balloon dilation.

Common Bile duct stones is one of the most common diseases of which the present incidence is 0.5% -3% in China. Endoscopic sphincterotomy (EST) is the most frequently used endoscopic technique for clearance of stones since the first description in 1974. Although EST is minimally invasive, it brings postoperative complications such as bleeding, perforation and acute pancreatitis. The overall complication and mortality is about 11.7-23% and 0.5%, respectively. Moreover, most believe EST can cause permanent sphincter of Oddi（SO） dysfunction which can result in biliary infection, stone recurrence and malignancies.

As an alternative method to EST, Endoscopic papillary balloon dilation (EPBD) was described by Staritz et al for the management of CBD stones. EPBD can preserve SO function and avoid undesirable effects due to an incompetent sphincter. It is reported that the basic SO function can be restored in one month after EPBD. Nonetheless, EPBD is indicated for the stones smaller than 12mm in diameters because the biliary orifice is enlarged to a lesser extent compared with EST. Furthermore, the incidence of postoperative pancreatitis reaches up to 15-30%. These disadvantages limit the application of EPBD.

As a result, Ersoz et al started a combined technique in 2003, which is called Endoscopic sphincterotomy with balloon dilation（ESBD）. ESBD can preserve SO function, reduce the adverse events, increase the stone removal rate. Especially, it can be applied for the stones larger than 12mm in diameters with large balloon dilatation. When ESBD is being performed, the duration of dilation is one of the most important factors affecting the postoperative complications. Whereas, there are issues regarding this technique that need further evaluation, such as the optimal duration of EPBD after EST. Some believe that short-term dilation can achieve the desired results and the duration of balloon dilation is not significantly correlated with postoperative pancreatitis, while opponents believe that although the small sphincterotomy is performed, short-term dilation has not been able to fully relax the residual sphincter. For long-term complications of ESBD, including the incidence of cholangitis, biliary stones recurrence rate, the incidence of biliary stenosis, there is no relative report either.

This prospective, randomized, controlled trial is designed to compare the difference of efficacy and morbidity among three different duration of balloon dilation（30s，60s，180s） after endoscopic sphincterotomy in the treatment of common bile duct stones. We hope that it will be helpful to establish the reasonable operation guidelines of ESBD.

Inclusion Criteria:

• CBD stone patients, age≥18 years
• Stone diameter≤1.5cm

Exclusion Criteria:

• Unwilling to consent for the study
• Previous EST or EPBD
• Prior surgery of Bismuth Ⅱ and Roux-en-Y
• Benign or malignant CBD stricture
• Preoperative coexistent diseases: acute pancreatitis, GI tract hemorrhage, severe liver disease, primary sclerosing cholangitis (PSC), septic shock
• Pregnant women