Radiologic Assessment for Endoscopic US-guided Biliary Drainage.

Endoscopic US-guided biliary drainage (BD) is performed for various types of biliary obstruction and is mainly indicated for unsuccessful conventional transpapillary endoscopic retrograde cholangiodrainage. In endoscopic US BD, an extra-anatomic drainage route between the gastrointestinal (GI) tract and the biliary system is created with a covered metallic stent or plastic stent. Procedural types of endoscopic US BD include hepaticogastrostomy, hepaticojejunostomy (after gastrectomy), choledochoduodenostomy, hepaticoduodenostomy, and endoscopic US-guided gallbladder drainage. The technical and clinical success rates of endoscopic US BD are reported to be 94%-97% and 88%-100%, respectively. CT is crucial both in preprocedural assessment and postprocedural monitoring. CT is used to determine the indications for endoscopic US BD, which include the type of biliary obstruction, collateral vessels in the puncture route, ascites, the volume of the liver segment, the distribution of an intrahepatic tumor, and GI tract patency. After endoscopic US BD, common subclinical findings are a small amount of intraperitoneal gas, localized edematous change in the GI tract, a notch in the placed stent, and localized biliary dilatation caused by stent placement. Stent malfunction after endoscopic US BD is caused by impaction of debris and/or food, stent migration into the GI tract, or tumor overgrowth and/or hyperplasia. Complications that can occur include internal stent migration, intraperitoneal biloma, arterial bleeding or pseudoaneurysm, perforation of the GI tract, and portobiliary fistula. The incidence of clinical endoscopic US BD-related complications is 11%-23%.