Sphincter of Oddi dysfunction and bile duct microlithiasis in acute idiopathic pancreatitis

Although there are numerous causes of acute panc-reatitis, an etiology cannot always be found. Two potential etiologies, microlithiasis and sphincter of Oddi dysfunction, are discussed in this review. Gallbladder microlithiasis, missed on transcutaneous ultrasound, is reported as the cause of idiopathic acute pancreatitis in a wide frequency range of 6%-80%. The best diagnostic technique for gallbladder microlithiasis is endoscopic ultrasound although biliary crystal analysis and empiric cholecystectomy remain as reasonable options. In contrast, in patients who are post-cholecystectomy, bile duct microlithiasis does not appear to have a role in the pathogenesis of acute pancreatitis. Sphincter of Oddi dysfunction is present in 30%-65% of patients with idiopathic acute recurrent pancreatitis in whom other diagnoses have been excluded. It is unclear if this sphincter dysfunction was the original etiology of the first episode of pancreatitis although it appears to have a causative role in recurring episodes since sphincter ablation decreases the frequency of recurrent attacks. Unfortunately, this conclusion is primarily based on small retrospective case series; larger prospective studies of the outcome of pancreatic sphincterotomy for SOD-associated acute pancreatitis are sorely needed. Another problem with this diagnosis and its treatment is the concern over potential procedure related complications from endoscopic retrograde cholangiopancreatography (ERCP), manometry and pancreatic sphincterotomy. For these reasons, patients should have recurrent acute pancreatitis, not a single episode, and have a careful informed consent before assessment of the sphincter of Oddi is undertaken.