Approach of suspected common bile duct stones: endoscopic ultrasonography.

Recent studies have shown that endoscopic ultrasonography (EUS) is the most sensitive method for diagnosing choledocholithiasis. High sensitivities of more than 95% have been reported by several authors. Imaging the extrahepatic bile ducts and the gallbladder and searching for biliary stones are easy tasks for EUS. EUS has the advantages over ERCP to be less invasive (complication rate similar to diagnostic upper GI endoscopy) and to be able to detect small stones and sludge that can easily be masked by contrast medium during ERCP. In comparison with magnetic resonance imaging (MRI), EUS has the advantage to be close to the investigated areas and to allow the detection of very small stones or sludge, even in non dilated bile ducts. Technical limitations of biliary imaging by EUS are few: upper GI stenosis, previous gastrectomy or Billroth II resection. Imaging can be obscured by the presence of air (previous sphincterotomy or surgical bypass), surgical clips calcifying pancreatitis or a duodenal diverticulum. Main indications of EUS include the detection of choledocholithiasis in patients with a low and intermediate probability of presence of stones, in idiopathic acute pancreatitis, in mild and moderate pancreatitis after normal transabdominal ultrasonography, in pregnant women, in intensive care patients, in the diagnosis of gallbladder lithiasis or sludge, and also when MRI is contraindicated (claustrophobia and metallic implants) or fails to provide a diagnosis or is not available. Screening of choledocholithiasis with EUS has also been proposed in patients scheduled for laparoscopic cholecystectomy, but this is not common practice in Belgium.