INTRODUCTION
Successful biliary interventions during endoscopic retrograde cholangiopancreatography (ERCP) rely upon selective and timely access to the biliary tree. Despite advances in ERCP techniques and accessories common bile duct cannulation may be unsuccessful in up to 5-15% of cases.25 Several advanced techniques for difficult biliary cannulation exist and are best utilized by experienced endoscopists in instances where standard biliary cannulation has failed. Advanced techniques such as needle-knife sphincterotomy, pre-cut fistulotomy, and transpancreatic pre-cut sphincterotomy have all been utilized for difficult biliary cannulation with varying rates of success. This review aims to present and compare some of the techniques that can be used when difficult biliary cannulation is experienced but will primarily focus on needle-knife sphincterotomy.