Review of Biliary Drainage in the Management for Preoperative and Unresectable Malignant Distal Biliary Obstructions

Endoscopic biliary drainage is recommended as a procedure for malignant distal biliary obstruction. A covered self-expandable metallic stent (SEMS) is preferable in patients undergoing preoperative chemotherapy for pancreatic cancer and recommended as the first-choice of biliary stent for unresectable malignant distal biliary obstruction, because of its long patency and possibility of removal in reintervention. However, a covered SEMS does not sufficiently reduce recurrent biliary obstruction (RBO) and prevent adverse events, and can even lead to occlusion by sludge formation and migration. Therefore, measures to prevent these disadvantages are urgently needed. It is important to understand the characteristics of various stents and to select the most appropriate stent for each case based on the likely need for reintervention for RBO or adverse events other than stent occlusion, as well as stent occlusion.