The aim of this study is to evaluate the usefulness of a newly developed multibending ultra-slim upper endoscope for the successful direct peroral cholangioscopy (POC) without assisting accessory in comparison with conventional ultra-slim endoscope. The investigators expect that multibending endoscope will show more higher successful performance than conventional endoscope.

Direct POC using an ultra-slim upper endoscope permits various diagnostic and/or therapeutic intraductal interventions under direct endoscopic visualization in selected patients who has dilated distal CBD and widened papillary orifice. Because the bile duct has anatomical position in acute angle with the duodenum, assisting accessories such as intraductal anchoring balloon, guidewire or overtube is usually required for the successful direct POC. Recently, direct peroral cholangioscopes have been developed for free-hand direct advancement of the endoscope into the bile duct from duodenum. Multibending ultra-slim endoscope may be expected to facilitate the advance into the bile duct by overcoming the acute angle between the bile duct and the duodenum. After randomization of enrolled patients into two groups, direct POC will be performed by using a conventional slim endoscope in control group and by using a multibending endoscope in study group.

Inclusion Criteria:

• Pancreatobiliary diseases that are indicated for direct POC
• The patient who aged from 20 to 80 years. Legally acceptable representative must be capable of giving written informed consent prior to participation in this study
• The woman of child-bearing age must be negative from the pregnancy test in order to participate in this study
• Dilated common bile duct (> 8 mm)
• Having previous sphincterotomy and/or papillary balloon dilation
• The patients should not have any unacceptable conditions (e.g., physiological, familyish, social, geographical) for medical follow-up and adaptation of the study.

Exclusion Criteria:

• Contraindicated for ERCP
• Patients with stricture on papillary orifice
• Patients with periampullary malignancy
• Bleeding tendency: International normalized ratio (INR) of prothrombin time < 1.5 or platelet count < 60,000/mm3
• Patients with other serious disease or medical condition
• Patients with past medical history of significant neurologic or Psychiatric disorders such as dementia or seizure
• Unstable heart disease despite of treatment, recent myocardial infarction within 6 month (Even though MI was diagnosed within 6 months, if it becomes stable presently, the patient can be possible to participate).