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

BACKGROUND AND STUDY AIMS

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.

PATIENTS AND METHODS

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).

RESULTS

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).

CONCLUSIONS

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.