Pancreatographic findings in idiopathic acute pancreatitis

Background/purpose Despite extensive evaluation based on clinical history, biochemical tests, and noninvasive imaging studies, the cause of acute pancreatitis cannot be determined in 10 to 30% of patients, and a diagnosis of idiopathic acute pancreatitis is made. The purpose of this study was to clarify the pancreatographic findings in patients with idiopathic acute pancreatitis.Methods Endoscopic retrograde cholangiopancreatography (ERCP) was performed in 34 patients with idiopathic acute pancreatitis, and the pancreatographic findings were examined. Patency of the accessory pancreatic duct was examined by dye-injection endoscopic retrograde pancreatography (ERP) in 16 of the 34 patients.Results In 11 patients (32%), the following anatomic abnormalities of the pancreatic or biliary system were demonstrated: complete pancreas divisum (n = 5), incomplete pancreas divisum (n = 2), high confluence of pancreaticobiliary ducts (n = 2), choledochocele (n = 1), and giant periampullary diverticulum (n = 1). Pancreatographic findings were normal in 17 patients. Eleven of these patients were examined by dye-injection ERP, and all were found to have nonpatent accessory pancreatic duct.Conclusions Anatomic abnormality of the pancreatic or biliary system is one of the major causes of idiopathic acute pancreatitis. Closure of the accessory pancreatic duct may play a role in the development of idiopathic acute pancreatitis in patients with a normal pancreaticobiliary ductal system.