Background: Conventional ultrasonography is used widely in the investigation of gallstone disease but is limited in the detection of bile duct stones due to poor visualization of the distal bile duct. Endoscopic retrograde cholangiopancreatography (ERCP) is currently the investigation of choice for suspected choledocholithiasis, but is not without morbidity. Endoscopic ultrasonography clearly visualizes the entire extrahepatic biliary tree and avoids the need for ERCP in many patients.
Methods: Some 50 patients with suspected duct stones underwent endoscopic ultrasonography followed by ERCP. All cholangiograms were performed or interpreted by a second doctor blinded to the results of endoscopic ultrasonography.
Results: Both tests were successful in 46 patients; both tests failed in two patients and ERCP alone failed in a further two. Duct stones were confirmed in 24 patients. Sensitivity (95 per cent confidence interval (c.i.)) of ERCP and endoscopic ultrasonography in identifying these stones was 79 (58-93) per cent and 88 (68-97) per cent respectively; specificity (95 per cent c.i.) was 92 (75-99) per cent and 96 (80-100) per cent.
Conclusion: Endoscopic ultrasonography accurately identifies bile duct stones. It is recommended in all patients with a risk of duct stones but especially in those with a history of ERCP-induced pancreatitis, when other pathology is suspected, when ERCP has failed, when bile duct abnormalities are suspected during pregnancy and in patients with acute pancreatitis.