Background and rationale Placement of biliary self expanding metal stent (SEMS) is indicated when malignant common bile duct obstruction is encountered.

Currently, there is still controversy regarding the use of endoscopic sphincterotomy (EST) before the placement of biliary stents. EST may facilitate insertion of self expandable metal stent (SEMS) and also help avert the development of pancreatitis from stent-related occlusion of the pancreatic duct. On the other hand, ES is also independently associated with pancreatitis, bleeding, and perforation.

Latest European guidelines indicate that EST is not necessary for inserting single plastic or metal biliary stents, nevertheless a more recent meta analysis showed that ES may decrease the rate of PEP.

Population and patient selection criteria All the patient referred for endoscopic retrograde cholangiopancreatography (ERCP) due to malignant bile duct obstruction.

Study design and study duration Prospective randomized, multicenter study. 18 months.

Description of study treatment/product/intervention All the patients will be randomly assigned to undergo ERCP with (Group A) or without (Group B) ES before biliary SEMS placement.

All the endoscopic procedures will be performed by experienced endoscopist in the endoscopy suite.

All the procedure will be conducted under deep sedation. SEMS placed will be fully covered.

Objectives To assess the need for EST before SEMS placement in patients with malignant bile duct obstruction.

To evaluate immediate (periprocedural) and delayed (30 days) post ERCP complications including pancreatitis, SEMS migration, bleeding and perforation.

Statistical methods, data analysis A sample size analysis to detect superiority at 5% significance level and a power of 80% showed that 500 patients had to be enrolled in each group.

Continuous variables such age will be reported in terms of their mean and range, and t-test will be done to test their main difference.

X square test or Fisher exact test will be carried out for statistical analysis to compare rates of total complications between the two groups and rates of pancreatitis, bleeding, stent migration and perforation.

Wilcoxon Mann-Withney test will be used for comparison of means between 2 continuous variables. A single-tailed P value of less than 0,05 is considered significant.

Study time table Project starting date: 15-7-2015 Project completion of patients accrual: 15-10-2016 Project completion of data collection: 15-11-2016 Project data analysis: 15-2-2017 Project presentation of scientific report: 15-4-2017

Inclusion Criteria:

• Patients referred for endoscopic retrograde cholangiopancreatography
• Malignant bile duct obstruction
• Signed written informed consent
• Age > 18

Exclusion Criteria:

• Inability to provide inform consent
• Pregnancy or lactation
• Suspected perforation of the GI tract
• Anatomical alterations due to previous surgery (Billroth surgery)
• Coagulation alterations