Current status of preoperative endoscopic biliary drainage for distal and hilar biliary obstruction.

The purpose of preoperative biliary drainage (PBD) is to reduce complications during the perioperative period. The extrahepatic bile duct comprises distal and hilar bile ducts and assessing the need for PBD must be considered separately for each duct, as surgical procedures and morbidities vary. The representative disease-causing distal bile duct obstruction is pancreatic cancer. A randomized controlled trial has revealed that PBD carries the risk of recurrent cholangitis and pancreatitis before surgery, thus eliminating the need for PBD when early surgery is feasible. However, neoadjuvant therapy has seen a rise in recent years, resulting in longer preoperative waiting periods and an increased demand for PBD. In such cases, metal stents are preferable to plastic stents due to their lower stent occlusion rates. When endoscopic transpapillary biliary drainage (EBD) is not viable, endoscopic ultrasound-guided biliary drainage may be a suitable substitute. In the hilar bile duct, the representative disease-causing obstruction is hilar cholangiocarcinoma. PBD's necessity has long been a subject of contention. In spite of earlier criticisms of routine PBD, recent views have emerged recommending PBD, particularly when major hepatectomy is required, to prevent postoperative liver failure. Given the risk of tumor seeding associated with percutaneous transhepatic biliary drainage, EBD is preferable. Nevertheless, as its shortcomings involve recurrent cholangitis until surgery due to stent or tube obstruction, it is necessary to seek out novel approaches to circumvent complications. In this review we summarize the current evidence for PBD in patients with distal and hilar biliary obstruction.