What Is the Impact of Biliary Intraductal Ultrasound in Daily Clinical Practice?

Abstract

Background: Intraductal ultrasound (IDUS) is useful for determining the nature of biliary strictures, staging of biliary cancer, and in detecting bile duct stones. There are limited published data on its actual clinical utility in a heterogeneous patient population undergoing endoscopic retrograde cholangiopancreatography (ERCP). Aim: This study evaluated the actual impact of biliary intraductal ultrasound in a heterogeneous patient population in daily clinical practice. Methods: This was a single center study conducted over a period of 20 months. The inclusion criterion was the need for adjunctive biliary IDUS when ERCP findings were indeterminate, such as the presence of strictures of unclear etiology or a seemingly normal cholangiogram without any filling defects when choledocholithiasis was suspected on basis of clinical presentation. Biliary IDUS was performed using a wire-guided mini-probe with 20MHz frequency (UM-G20-29R, Olympus, Tokyo, Japan). A true positive was defined on basis of results of brush cytology or surgical histology, or through documentation of actual stone extraction in the context of suspected common bile duct (CBD) stones. Patients with negative IDUS findings were followed up and considered true negatives in the absence of clinical symptoms and normal liver function tests at 6-month follow up. A positive clinical impact was defined as achieving a positive clinical diagnosis or affecting subsequent management strategy. Results: Forty-five (8.2%) of 552 patients who underwent ERCP had indeterminate ERCP findings that required further evaluation with biliary IDUS. IDUS was technically successful in all cases. The mean age was 60.7 years (range: 33 - 92), with 62.2% male. ERCP showed apparently normal CBD in 22 (48.9%), dilated CBD of unclear etiology in 8 (17.8%) and a CBD stricture in 15 (33.3%) patients. Among the patients with either apparently normal CBD or dilated CBD of unclear etiology, an occult CBD stone (mean size 2.5mm; range: 1.1 - 6.6) was found in 27/30 (90%), with the remaining cases being normal. Among patients with strictures, Mirizzi syndrome was diagnosed in 7/15 (46.7%), cholangiocarcinoma in 4/15 (26.7%), malignant IPMN in 1/15 (6.7%) and benign fibrotic stricture in 2/15 (13.3%). One patient with biliary stricture was wrongly diagnosed as biliary hydatid disease based on a cystic appearance; subsequent surgery revealed hepatobiliary cystademona. Overall biliary IDUS had a positive clinical impact in 39/45 (86.7%). Conclusion: Biliary IDUS increases the diagnostic accuracy of ERCP. It is a very useful adjunctive test when ERCP findings are indeterminate.