Endoscopic ultrasound-guided biliary drainage for biliary obstruction

2.1 Biliary obstruction involves blockage of any duct that carries bile from the liver to the gallbladder or from the gallbladder to the small intestine. It may have benign or malignant causes, and can lead to symptoms including jaundice, nausea and abdominal pain, itching, pale stools and dark urine.

2.2 Current standard management of biliary obstruction usually includes stenting using endoscopic retrograde cholangiopancreatography (ERCP) or percutaneous transhepatic biliary drainage (PTBD). For malignant obstruction, treatment may also include chemotherapy, biological therapy, photodynamic therapy and radiofrequency ablation.

2.3 Endoscopic ultrasound-guided biliary drainage (EUS‑BD) is an alternative procedure when ERCP is not possible; ERCP fails in a small proportion of people because of the nature of the obstruction or their anatomy (which may be altered because of disease progression or previous surgery). EUS‑BD is also a minimally invasive alternative to PTBD, which is conventionally offered when ERCP has failed. The aim of the procedure is to reduce biliary obstruction and allow the biliary tract to drain.

2.4 EUS‑BD may be done under conscious sedation or general anaesthesia. It involves inserting an echoendoscope through the mouth and oesophagus into the stomach or duodenum. Using ultrasound guidance, the biliary tract is punctured with a needle. A contrast agent may be injected to enhance imaging.

2.5 A guidewire is then passed into the biliary tract at the site of the puncture, which is dilated to create a fistula. Finally, a metal or plastic stent is deployed into the biliary tract to allow biliary drainage into the stomach or small intestine. Stent delivery systems may also be used to do EUS‑BD without needle puncture, dilation or insertion of a guidewire.

2.6 EUS‑BD can be done using several different techniques and stents can be deployed through multiple access routes. The 2 most common techniques, endoscopic ultrasound-guided choledochoduodenostomy (EUS‑CDS) and endoscopic ultrasound-guided hepaticogastrostomy (EUS‑HGS), both use a transluminal approach. In EUS‑CDS, the extrahepatic bile duct is punctured, and the stent is deployed via the duodenal bulb. In EUS‑HGS, the left hepatic duct is punctured, and the stent is deployed via the stomach.

2.7 Stents may also be deployed using a transpapillary approach in which the guidewire is passed into the duodenum. In endoscopic ultrasound-guided antegrade stenting (EUS‑AGS), the stent is placed across the biliary obstruction. In the endoscopic ultrasound-guided rendezvous technique (EUS‑RV), the echoendoscope is swapped with an ERCP duodenoscope after placement of the guidewire, and a conventional ERCP is done before stent placement. The choice of technique depends on the cause of the biliary obstruction and the anatomy of the person having the procedure.