Detection of choledocholithiasis: Comparison of unenhanced spiral CT, US, and ERCP

Background/Aims: ERCP is an established method for the diagnosis and treatm ent of common bite duct stones; however, it is invasive, time-consuming, an d expensive. The purpose of this study was to determine whether unenhanced spiral CT and US, compared with ERCP, have sufficient sensitivity and negat ive predictive value to be useful screening techniques in patients suspecte d of having choledocholithiasis. Methodology: Over a period of 2 years, 82 patients with clinically suspecte d choledocholithiasis underwent unenhanced spiral computed tomography and U S immediately before undergoing endoscopic retrograde cholangiopancreatogra phy. CT/US scans and ERCP images were evaluated for the presence of bile du ct stones, ampullary stones, and extrahepatic biliary dilatation. Results: Unenhanced spiral computed tomography (US) depicted common bile du ct stones in 24 (23) of 28 patients found to have stones at endoscopic retr ograde cholangiopancreatography. Five patients had stones impacted at the a mpulla, all (two) of which were detected with CT (US). Computed tomography (US) had a sensitivity of 86% (82%) and a specificity of 98% (98%) in the d iagnosis of choledocholithiasis. Conclusions: Both unenhanced spiral CT and US are useful for evaluating sus pected common bile duct stones. Unenhanced spiral CT is especially useful w hen the patient is likely to have ampullary stones and is a safe, more avai lable and less expensive alternative to magnetic resonance cholangiography.