Technical tips and troubleshooting of endoscopic biliary drainage for unresectable malignant hilar biliary obstruction

Unresectable malignant hilar biliary obstruction (MHBO) occurs in various diseases, such as cholangiocarcinoma, gallbladder carcinoma, hepatocellular carcinoma, pancreatic cancer, and lymph node metastasis of the hilum of the liver. The majority of patients with advanced MHBO are not candidates for surgical resection because of the tumor location in the hepatic hilum and adjacent areas, advanced tumor stage, or comorbidities. Therefore, these patients often have a poor prognosis in terms of survival and quality of life. Most of these patients will require non-surgical, palliative biliary drainage. To date, various biliary drainage techniques for unresectable MHBO (UMHBO) have been reported. Of these techniques, endoscopic biliary drainage is currently considered to be the most safe and minimally invasive procedure. However, endoscopic biliary drainage for UMHBO is still not standardized regarding the optimal stent, drainage area, stenting method, and reintervention technique. Recently, towards standardization of this technique for UMHBO, clinical research and trials including randomized controlled trials have been performed. In this article, we reviewed the most important issues regarding endoscopic biliary drainage for UMHBO, focusing on prospective studies. We also described in detail the techniques and future perspectives of endoscopic biliary drainage in patients with UMHBO.