Acute idiopathic pancreatitis: Does it really exist or is it a myth?

Background: Acute pancreatitis is a severe disease with considerable morbidity and mortality. Gallstones and alcohol abuse are the most frequent causes (75% of patients). Other well-known causes are: hyperlipidemia, hypercalcaemia, abdominal surgery and drugs. In 10%-40% of patients however, no cause is identified after initial diagnostic evaluation: acute idiopathic pancreatitis. Identifying a cause in these patients is important, since the recurrence rate is high. Methods: A systematic review of the current literature was performed to identify possible causes, diagnoses and treatment options of acute idiopathic pancreatitis. Relevant literature was found via Pubmed. Results: The presence of microlithiasis or biliary sludge is an important cause of acute 'idiopathic' pancreatitis (up to 80% of patients). Microlithiasis and sludge can be detected by transabdominal/endoscopic ultrasonography, ERCP or polarizing light microscopy of bile. Cholecystectomy is the treatment of choice, whereas endoscopic sphincterotomy and ursodeoxycholic acid maintenance therapy are effective alternatives. Sphincter of Oddi dysfunction can be identified as the cause of acute 'idiopathic' pancreatitis in up to 30% of patients. Manometry of Oddi's sphincter is the gold standard for its diagnosis. Endoscopic sphincterotomy prevents recurrence in most patients. Anatomic abnormalities such as major papilla stenosis, pancreas divisum, pancreatic duct strictures and tumours may also cause acute 'idiopathic' pancreatitis. Endoscopic sphincterotomy and surgery are effective treatments. Finally, genetic screening may reveal gene mutations as the cause of acute 'idiopathic' pancreatitis. Conclusions: Acute 'idiopathic' pancreatitis is a severe disease with a high recurrence rate. Extensive diagnostic investigations may lead to a cause in >90% of patients.