Background: An imaging modality that can be used to identity small stones after a biliary lithotripsy is required. Intraductal ultrasonography was evaluated by using percutaneous transhepatic cholangioscopy as the gold standard.
Methods: Lithotripsy, under percutaneous transhepatic cholangioscopy guidance, was performed in 20 patients. A thin-caliber ultrasonic probe (2.0 mm in diameter and 20 MHz frequency) was inserted into the bile duct through the percutaneous tract after lithotripsy, and residual stones were identified. This was followed by percutaneous transhepatic cholangioscopy.
Results: In the extrahepatic bile ducts, intraductal ultrasonography provided images of all the stones demonstrated on cholangioscopy (n = 11). The sensitivity was superior to that of cholangiography (P < 0.005). However, in the intrahepatic bile ducts, intraductal ultrasonography only visualized the stones located in the cannulated lobe. Extrahepatic stones smaller than 5.0 mm in diameter or in a common hepatic duct larger than 15.0 mm in diameter were missed by cholangiography, but were visualized by the use of intraductal ultrasonography (P < 0.05).
Conclusions: Intraductal ultrasonography is equivalent to cholangioscopy in the extrahepatic bile ducts. Cholangiography and intraductal ultrasonography should be used in combination to image intrahepatic and extrahepatic stones.