Fig. 1. (A) Magnetic resonance cholangiopancreatography imaging revealed an uncommon dilated common bile duct. (B) Computed tomography imaging three years before indicated the presence of a small periampullary diverticulum (arrow). (C) Endoscopic findings did not confirm the presence of the periampullary diverticulum.

Fig. 2. (A) Endoscopic retrograde cholangiopancreatography revealed the guidewire forming a loop in the bile duct. (B) After the cannulation catheter was pulled into the duodenal lumen at the endoscopic downward angle, the oral protrusion of the papilla of Vater was partially extruded from the periampullary diverticulum (PAD). (C) Endoscopic findings indicated the successful correction of the incarceration of the large oral protrusion of the papilla of Vater within the PAD by using the sphincterotome. (D) Endoscopic findings revealed the presence of PAD (arrow). (E) Following the correction of the papillary incarceration, biliary tract cannulation became feasible.