[Acute cholangitis: imaging diagnosis and management]

Cholangitis is an infection of the biliary ductal system that results from biliary obstruction. Choledocholithiasis has been the leading cause of acute cholangitis. Acute cholangitis remains a life-threatening complication of biliary obstruction that needs emergency diagnosis and treatment. Ultrasound (US) is the primary imaging modality for assessment of patients with suspected acute cholangitis. US is both sensitive and specific in demonstrating biliary dilatation. However, biliary dilatation is not always present at the early stage of bile duct obstruction and the performance of US in demonstrating choledocholithiasis is poor. Computed tomography (CT) without contrast injection is more sensitive than US in demonstrating choledocholithiasis. Magnetic resonance cholangiopancreatography (MRCP) and endoscopic sonography (EUS) are the most sensitive techniques to correctly determine the underlying cause and level of biliary obstruction in patients with acute cholangitis. In patients without previous cholecystectomy, clinical, biological, and US results allow to determine patients with high probability of having choledocholithiasis even if the stone is not directly visible on US. Patients undergoing cholecystectomy require laparoscopic common bile duct exploration, especially if the common bile duct clearance is not checked before surgery by MRCP or EUS.