Malignant obstructive jaundice is a common complication of advanced stage cholangiocarcinoma, GB cancer, and pancreatic cancer. In biliary stricture by malignancy, biliary drainage with placement of self-expanding metal stent (SEMS) for palliation is the therapy of choice in these patients. On hilar biliary malignant obstruction, bilateral stent used to be inserted. There are two kinds of bilateral metal stent insertion methods in hilar biliary malignant obstruction. (Stent in stent vs. side by side) Previously, two studies was conducted to show the superiority of bilateral metal stent insertion between stent in stent and side by side. Biliary drainage and stent patency was a little superior in side by side than stent in stent. But, complication related with bilateral metal stent was increased in patients with side by side method. Another study showed that there was no significant difference between those bilateral stent insertion methods. The most important concern about side by side method is associated with portal vein thrombosis by bilateral stent diameter. Selection of proper stent insertion method in patients with hilar malignant biliary obstruction is still controversial.

The purpose of this study is to investigate the patency of stent and survival of patients in side by side method (6mm sized M type) compared to stent in stent method (10mm sized LCD type) in patient with hilar malignant biliary obstruction.

Inclusion Criteria:

• Pathologically confirmed hilar malignant biliary obstruction or clinically defined malignant biliary obstruction
• older than 20 years old

Exclusion Criteria:

• Operable case
• Non-hilar biliary malignant obstruction
• Duodenal obstruction
• Other cancer except biliary malignancy
• uncontrolled infection status
• Eastern Cooperative Oncology Group ≥ 3
• No signed informed consent
• Failed endoscopic approach to duodenum or biliary tract