Over-the-wire US catheter probe as an adjunct to ERCP in the detection of choledocholithiasis

Background. Intraductal ultrasound (IDUS) as an adjunct to ERCP for detecti on 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 duo denoscope into the bile duct without performing a sphincterotomy. All stone s 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 d uct diameter ranged from 0.6 to 2.3 cm and stone size from 2 mm to 2 cm. ID US successfully identified all stones in these patients. IDUS resulted in 2 false-positive diagnoses in the remaining 6 patients without stones (overa ll accuracy 97%, sensitivity 100%, specificity 67%). Cholangiography detect ed 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 ca nnulated duct. IDUS is an excellent adjunct to ERCP for the diagnosis of ch oledocholithiasis. IDUS differentiates stones from air bubbles and prevents unnecessary sphincterotomy.