New Classification for the Accessory Pancreatic Duct by ERP

The head of the pancreas is formed embryologically from two anlage. The pancreatic duct system in the head is a complex structure. We devised a new classification for the accessory pancreatic duct (APD) based on the junctional point of the APD and the main pancreatic duct (MPD) in addition to the shape of the APD, which was found to be applicable to most cases. We reviewed 385 random endoscopic retrograde pancreatograms of normal pancreatic head of the pancreas which demonstrated satisfactory imaging of the entire APD. All accessory duct pancreatograms could be classified into four types according to the length of the MPD from the orifice to the junction with the APD, as well as the shape of the APD. The APD joined with the MPD at the neck portion in the long type, between the first inferior and superior branches of the MPD in the intermediate type, and near the first inferior branch of the MPD in the short type. The APD had an arched course over the MPD in the ansa type. The APD of the long type frequently exhibited a straight course from the upper dorsal pancreatic duct, representing a persistent main drainage duct of the dorsal pancreatic primordium. This novel clasification may be adapted to most cases and may reflect the embryogenesis of the APD.