Pancreatographic Findings of Idiopathic Acute Pancreatitis

Abstract

Background/Aims: Despite extensive evaluation based on clinical history, biochemical tests, and noninvasive imaging studies, a cause is not established in 10 to 30% of acute pancreatitis cases and a diagnosis of idiopathic acute pancreatitis is made. Aim of this study is to clarify the pancreatographic findings of patients with idiopathic acute pancreatitis. Methods: We performed ERCP in 187 patients with acute pancreatitis after clinical and biochemical resolution of pancreatitis. Thirty-six patients (20 males and 16 females, average age 48.1 years at diagnosis) were diagnosed as having idiopathic acute pancreatitis. Exclusion criteria for idiopathic acute pancreatitis were a history of alcohol abuse; evidence of cholelithiasis and/or choledocholithiasis on US, CT, and ERCP; hypercalcemia; hyperlipidemia; history of trauma; postoperative state; chronic pancreatitis; and having ingested a drug known to be associated with pancreatitis within 1 month of examination. No patients had family histories of pancreatitis. Pancreatographic findings of these 36 patients were examined. Patency of the accessory pancreatic duct was examined by dye-injection ERP in 17 of the patients. After routine ERP studies, contrast medium containing indigo carmine was injected into the main pancreatic duct through a catheter under usual pressure, and the egress of the dye from the minor duodenal papilla was examined endoscopically. Results: In 13 patients (36%), the following anatomic abnormalities of the pancreatic or biliary system were demonstrated: complete pancreas divisum (n=5), incomplete pancreas divisum (n=2), congenital choledochal cyst (n=2), high confluence of pancreaticobiliary ducts (n=2), choledochocele (n=1), and giant periampullary diverticle (n=1). Marked narrow main pancreatic duct was demonstrated in 3 patients, and 3 patients showed a slightly dilated entire main pancreatic duct suggesting papillary stenosis. Pancreatographic findings were normal in the remaining17 patients. Eleven of these 17 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 was one of the major causes of idiopathic acute pancreatitis. Nonpatency of the accessory pancreatic duct might play a role in the development of idiopathic acute pancreatitis in the normal cholangiopancreatic ductal system.