Narrow portion of the terminal choledochus is a cause of upstream biliary dilatation in patients with anomalous union of the pancreatic and biliary ducts

Figure 1 Endoscopic retrograde cholangiopancreatogram in a 55-year-old woman with gallbladder cancer associated with AUPBD and cylindrical biliary dilatation (A). Diagram of the cholangiopancreatogram (B). The minimum diameter of the narrow portion of the terminal choledochus is 4 mm, and the maximum diameter of the upstream choledochus is 15 mm. AUPBD: anomalous union of the pancreatic and biliary ducts; NDS: narrow distal segment; P-B ductal union: pancreaticobiliary ductal union; narrow portion: narrow portion of the terminal choledochus; MPD: main pancreatic duct.