Catheter probe extraductal ultrasonography vs. conventional endoscopic ultrasonography for detection of bile duct stones

Abstract

Endoscopic ultrasonography (EUS) has been established as a valuable diagnostic tool for the detection of bile duct stones (BDS). The recently introduced extraductal endoscopic ultrasonography (EDUS) using miniprobes has the advantage that it can be performed with a duodenoscope, and if therapeutic interventions become necessary, there is no need to change the scope. Consecutive patients with acute biliary pain and a dilated bile duct and/or elevated liver function tests, in whom the origin of biliary obstruction could not be identified by US and CT, were enrolled. The patients were investigated with a linear-array echoendoscope, and an additional transduodenal EDUS examination was performed with a 12-MHz miniprobe via the instrumentation channel of the echoendoscope. The presence or absence of BDS was afterwards evaluated by endoscopic retrograde cholangiopancreatography (ERCP)/sphincterotomy (EST) and by instrumental bile duct exploration (in the case of a positive EUS/EDUS finding), or by magnetic resonance cholangiopancreatography (MRCP) and ERCP with additional clinical follow-up (in the case of negative findings on EUS/EDUS). One hundred and fifty-five patients (55 +/- 12 years old, 98 female) were enrolled. In six cases, the distal bile duct could not be successfully visualized by EDUS, whereas with EUS visualization failed in only one patient ( P = 0.13). Choledocholithiasis was proven in 75 cases (48 %). The diagnostic accuracy of EUS for the detection of BDS (sensitivity 92 %, specificity 100 %, PPV 1.0, NPV 0.93, accuracy 95 %) was comparable to that of EDUS (sensitivity 90 %, specificity 98 %, PPV 0.99, NPV 0.93, accuracy 91 %, P = 0.17 vs. EUS). In patients at intermediate risk of BDS it seems to be justified to perform EDUS instead of EUS, and to proceed with ERCP and EST immediately when findings are positive.