Role of endoscopic ultrasound in evaluation of patients with missed common bile duct stones.

Background: Choledocholithiasis develops in up to 20% of patients with gall bladder stones. The challenge in diagnosis usually occurs with small stones that may be missed by magnetic resonance cholangiopancreatography (MRCP). Endoscopic ultrasound (EUS) is accurate in detecting common bile duct (CBD) stones missed by MRCP, especially the small ones or those impacted at the distal CBD or the papillary region.

Aim: To evaluate the accuracy of EUS in detecting CBD stones missed by MRCP.

Methods: Patients with an intermediate likelihood of choledocholithiasis according to ESGE guidelines and those with acute pancreatitis of undetermined cause were included. The presence of choledocholithiasis was evaluated by MRCP and EUS, and then results were confirmed by endoscopic retrograde cholangiopancreatography (ERCP). The sensitivity and specificity of EUS and MRCP were compared regarding the presence of stones, the size, and the number of detected stones.

Results: Ninety out of 100 involved patients had choledocholithiasis, while ten patients were excluded as they had pancreatic or gall bladder masses during EUS examination. In choledocholithiasis patients, the mean age was 52.37 ± 14.64 years, and 52.2% were males. Most patients had biliary obstruction (74.4%), while only 23 (25.6%) patients had unexplained pancreatitis. The overall prevalence of choledocholithiasis was 83.3% by EUS, 41.1% by MRCP, and 74.4% by ERCP. Also, the number and size of CBD stones could be detected accurately in 78.2% and 75.6% by EUS and 41.1% and 70.3% by MRCP, respectively. The sensitivity of EUS was higher than that of MRCP (98.51% 55.22%), and their predictive value was statistically different ( 0.001). Combination of both tools raised the sensitivity to 97.22% and specificity to 100%.

Conclusion: EUS could be a useful tool in assessing patients with suspected choledocholithiasis especially if combined with MRCP. However, its usefulness depends on its availability and the experience of the local centers.