Single Plastic Stent Vs. Fully Covered Self-Expanding Metal Stent on Benign Biliary Stricture Secondary to Chronic Pancreatitis

Inclusion Criteria: 1. Age 18 or older; 2. Patients diagnosed with CP; 3. Symptomatic biliary stricture documented at time of enrollment for naïve stricture or at the time of prior plastic stent placement in strictures that had 1 prior plastic stent inserted: cholangitis, and/or an increase in total bilirubin or alkaline phosphatase levels(\> 2 times the upper limit of normal) for more than 4 weeks; 4. Confirmation of bile duct stricture by imaging assessment. Exclusion Criteria: 1. Prior plastic stenting exceeding six months or any metal stenting; 2. Incomplete removal of stones from the main pancreatic duct located in the head of the pancreas during ERCP procedures; 3. Biliary stricture of benign etiology other than chronic pancreatitis; 4. Developing obstructive biliary symptoms associated with an attack of acute pancreatitis; 5. Stricture within 2 cm of common bile duct bifurcation; 6. Biliary stricture of malignant etiology; 7. Patients with acute or chronic hepatitis, cirrhosis, primary sclerosing cholangitis, congenital biliary malformations or biliary fistula; 8. Symptomatic duodenal stenosis (with gastric stasis); 9. Subjects for whom endoscopic techniques are contraindicated; 10. Pregnancy, incarceration; 11. Life expectancy \< 1 year; 12. Other conditions that inappropriate to participant in the study.