Intraduodenal acetic acid can stimulate secretion of water and bicarbonate from pancreatic ductal cells. In this study, acetic acid spraying to duodenal bulb was compared with saline solution for the facilitation of pancreatic duct cannulation in patients.The primary outcome was successful deep pancreatic duct cannulation. The secondary outcomes were the appearance of the major and minor papillary orifice, pancreatic juice flow from the papilla, time to achieve deep pancreatic duct cannulation, and fluoroscopy time for deep pancreatic duct cannulation in the acetic acid group versus saline group.

Inclusion Criteria:

• Inclusion criteria were(1)those with intact native papilla (2)who underwent endoscopic retrograde choledochopancreatography for pancreatic duct, (3)age≥18 years，≦80years,and (4)agreement to participate in the study.

Exclusion Criteria:

• Exclusion criteria were (1) a previous sphincterotomy, (2) previous attempted or unsuccessful endoscopic retrograde choledochopancreatography with papillary manipulation, (3) indwelling biliary or pancreatic stent(s), (4) active acute pancreatitis, (5) altered/postsurgical anatomy, (6) history of gastroparesis, and (7) endoscopic retrograde choledochopancreatography for sphincter of Oddi (SO) manometry.