Magnetic resonance imaging of the common bile duct to exclude choledocholithiasis

Background: Prior to cholecystectomy it is important to assess the common duct for choledocholithiasis. Given that a proportion of common duct stones will pass without incident and that methods of removal of these stones are potentially morbid, it would be very useful to have a test that identified only those stones that need intervention. The present study was designed to assess whether a negative magnetic resonance cholangiopancreaticogram (MRCP) is able to reliably exclude clinically relevant common duct stones. Methods: A retrospective analysis on all patients with cholelithiasis, who underwent MRCP, between November 2001 and May 2003, for suspected choledocholithiasis, was performed. Patients were considered to have no clinically relevant choledocholithiasis if they had a negative MRCP for choledocholithiasis, and were not readmitted to the hospital with complications of choledocholithiasis within a minimum of 3 months after treatment for their cholelithiasis. Results: The MRCP was negative for choledocholithiasis in 74% of patients (60/81). The MRCP missed clinically relevant choledocholithiasis in only two patients, and had a positive predictive value of 0.95 and a negative predictive value of 0.97 for choledocholithiasis. Conclusion: In patients with strong indications for choledocholithiasis MRCP is able to reliably exclude clinically relevant choledocholithiasis and is therefore recommended as the preoperative diagnostic imaging tool of choice.