Pancreas divisum is the most common congenital anomaly of the pancreas.  It occurs in approximately 7% of autopsy series (range, 1-14%). The frequency of finding this condition varies greatly in endoscopic retrograde cholangiopancreatography (ERCP) series (4-25%), depending on the population studied and the degree to which complete pancreatography is pursued.
Pancreas divisum develops prenatally. It is caused by the failure of the ducts of the dorsal and ventral buds to fuse during embryologic development, at approximately the eighth week of intrauterine life. In more than 90% of individuals, the proximal one third of the dorsal pancreatic duct regresses as it fuses with the ventral duct, forming the main pancreatic duct.
In the remainder, one of the following occurs. In cases of classic pancreas divisum, the small ventral duct, or duct of Wirsung, drains via the major papilla and the large dorsal duct, or duct of Santorini, drains via minor papilla. Cases of incomplete pancreas divisum are the same as classic divisum, except a small branch connects the ventral and dorsal pancreas. In cases of pancreas divisum with nonpatent major papilla, the entire pancreatic ductal system drains via the minor papilla. In cases of reversed pancreas divisum, the small dorsal duct drains via minor papilla and the large ventral duct drains via major ampulla. This variant has no physiologic significance except in rare cases of pancreatic cancer that do not involve the main pancreatic duct.
Symptoms of pancreatic divisum probably are due to high intrapancreatic dorsal ductal pressure caused by resistance to pancreatic secretion by a small minor papilla orifice. Possible alternate mechanism is intermittent obstruction of drainage by minor papilla proteinaceous plugs.  CFTR gene mutation has been found in some cases of pancreas divisum and may be responsible for variations in the occurrences of symptoms. [3, 4, 5, 6, 7]
It occurs in approximately 7% of autopsy series (range, 1-14%). The frequency of finding this condition varies greatly in ERCP series (4-25%), depending on the population studied and the degree to which complete pancreatography is pursued. Pancreas divisum has geographic variations and is found in approximately 4-10% of the white population and 1-2% of the Asian population. [8, 9, 10] Geographic variation could be secondary to thea diagnostic procedure used.