Background: Intraductal ultrasound (IDUS) as an adjunct to ERCP for detection of extrahepatic bile duct stones is technically easy, accurate, and safe. This prospective study evaluated IDUS with an "over-the-wire" catheter US probe as an adjunct to ERCP.
Methods: Sixty-five patients, highly suspected to have choledocholithiasis, underwent IDUS during ERCP. The IDUS probe was inserted by means of the duodenoscope into the bile duct without performing a sphincterotomy. All stones identified by IDUS or retrograde cholangiography were removed with either a basket or retrieval balloon after endoscopic sphincterotomy.
Results: The final diagnosis was choledocholithiasis in 59 patients. Bile duct diameter ranged from 0.6 to 2.3 cm and stone size from 2 mm to 2 cm. IDUS successfully identified all stones in these patients. IDUS resulted in 2 false-positive diagnoses in the remaining 6 patients without stones (overall accuracy 97%, sensitivity 100%, specificity 67%). Cholangiography detected stones in 55 of the patients with stones (accuracy 94%, sensitivity 93%, specificity 100%).
Conclusion: IDUS, a safe, technically easy procedure, is highly accurate in the detection of extrahepatic bile duct stones regardless of the diameter of the bile ducts. The "over-the-wire" technique preserves access to the cannulated duct. IDUS is an excellent adjunct to ERCP for the diagnosis of choledocholithiasis. IDUS differentiates stones from air bubbles and prevents unnecessary sphincterotomy.