A sphincterotome was used for standard wire-guided cannulation. If the difficult biliary cannulation occurred and guidewire inadvertently entered PD, a tiny cut of opening, with the length of 5mm, was performed with the sphincterotome. Then the guidewire was left in PD and the sphincterotome withdrew. The same sphincterotome was re-inserted in the working channel alongside the first guidewire, another wire is used for wire-guided selective cannulation of CBD. If the cannulation of CBD was not successful within 5 attempts, other cannulation techniques (e.g. transpancreatic precut, needle knife (NK) precut or over-the stent precut) would be tried at the discretion of endoscopists. A 5Fr, unflanged PD stent was placed before the ending of ERCP.

A sphincterotome was used for standard wire-guided cannulation. If the difficult biliary cannulation occurred and guidewire inadvertently entered PD, the guidewire was left in PD and the sphincterotome withdrew. The same sphincterotome was re-inserted in the working channel alongside the first guidewire, another wire is used for wire-guided selective cannulation of CBD. If the cannulation of CBD was not successful within 5 attempts, other cannulation techniques (e.g. transpancreatic precut, NK precut or over-the stent precut) would be tried at the discretion of endoscopists. A 5Fr, unflanged PD stent was placed before the ending of ERCP.

For experimental arm, a tiny cut of papilla orifice, with the length of 5mm, was performed by sphincterotome before the double wire cannulation.

the rate of successful cannulation of CBD for ≤5 attempts by using the sphincterotome alongside the PD guidewire.

the time taken from the touching of papilla by the sphincterotome alongside the PD guidewire to the successful cannulation of CBD