The purpose of this study is to determine how different endoscopic papillary balloon dilatation (EPBD) duration time affects the complications after endoscopic retrograde cholangiopancreatography (ERCP) in the treatment of common bile duct stones.

Common bile duct (CBD) stone is a common disease with high morbidity. Half century ago, surgery with bile duct exploration and T-tube drainage was the only radical treatment for the stones until a revolutionary technique was reported in 1970, which possible to remove stone by means of endoscopic sphincterotomy (EST) during endoscopic retrograde cholangiopancreatography (ERCP). Since then, EST became a very promising measure for both patients and doctors to meet the purpose of minimally invasive treatment. However, EST remains an advanced technique which requires high skills of the endoscopist. As far as patients who have anatomical biliary abnormalities, such as papillary diverticulum, are more likely to end up with severe complications such as bleeding and perforation during EST procedure. On the other hand, EST may also lead to permanent dysfunction of the Oddi's sphincter. It is currently reported that a growing number of young patients, even some children are managed with EST which is still debated due to the existence of some long-term complications.

Endoscopic papillary balloon dilatation (EPBD) is an alternative technique developed to achieve the same purpose as EST but preserving Oddi's sphincter' function partially, and more than that, EPBD is easy to grasp for endoscopist. By using a columnar balloon, Oddi's sphincter can be expanded without direct transection, and the temporary relaxation of Oddi's sphincter makes it possible to remove the stones and the rest of the procedures as well. Removing common bile duct stone by EPBD was firstly reported in 1982 and proved to be safe and efficient. However, clinical observations have been found that simple EPBD has a higher incidence of developing acute pancreatitis after ERCP, especially in patients with intact papilla. The speculated reason for high post-ERCP pancreatitis (PEP) rate might be pancreatic duct orifice edema resulted from inadequate destroy of Oddi's sphincter during a balloon dilatation, leading the pancreatic duct obstructed and high ductal pressure afterward. Retrospective study has indicated the PEP rate of post-EPBD by 10% which was considered slightly higher than ordinary EST before a new modified method has been introduced by a small EST prior to EPBD. Currently small EST plus EPBD has been increasingly used in clinical and proven to be an effective treatment for improving the success rate of the common bile duct stone removal, preserving Oddi's sphincter function and lowering long-term complications.

Dedicate practitioners conducted many kinds of studies about reducing post-ERCP complications, and nowadays, some of them focus on the dilation time of EPBD which would be suspected as the key point of the issues. Nonetheless, more institutes are willing to join in EPBD research as the universal concerns for post-ERCP complications increases, no common agreements achieved at present.

From some prospected data, we might see confused results. Slowly inject balloon with a contrast agent and keep dilating for 1-2 minutes, until 15 seconds after the image of papilla and balloon waist disappeared is able to get the same stone removal rate as regular procedure does, and a slower balloon filling performance is helpful to protect the Oddi's sphincter function and reduce post-ERCP complications. However, other studies conclude there are no difference no matter in stone removal rate or post-ERCP pancreatitis instead of blood amylase, in which arms are 20 seconds compared 60 seconds and 30 seconds compared 60 seconds. Interestingly, there is another inspiring randomized controlled trial (RCT) study which prolong the dilation time up to 5 minutes. The author figured that PEP rate of five minutes group is smaller than that of the 1-minute group as well as stone removal.

Few studies concerning the optimal duration time of EPBD which is very important to patients' safety and maximum utilization of the easier handled EPBD procedure compared to EST. Therefore this large volume multicenter prospective randomize control study targets on how different EPBD duration management affect the complications after ERCP which attempts to discover a promising method for safe therapy in common bile duct stones.

Inclusion Criteria:

• Age≥18 years
• CBD stone patients, stone diameter≤1.5cm, CBD diameter≤2cm

Exclusion Criteria:

• Unwillingness or inability to consent for the study
• Coagulation dysfunction (INR> 1.3) and low peripheral blood platelet count (<50×109 / L) or using anti-coagulation drugs
• 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
• Combined with Mirizzi syndrome and intrahepatic bile duct stones
• Malignant disease
• Biliary-duodenal fistula confirmed during ERCP
• Pregnant women