Examination of major duodenal papilla (MDP) using a side-viewing duodenoscope is a golden standard. However, side-viewing duodenoscope is not available in some endoscopic centers. Cap-assisted esophagogastroduodenoscopy (Ca-EGD) using a transparent cap fitted to the tip of the scope has emerged as an alternative method for the observation of MDP. A recent study showed that complete examination of MDP could be achieved in 97% of patients. The investigators hypothesize that Ca-EGD is non-inferior to duodenoscope for the observation of MDP.

Interim analyses were planned to be performed by the data and safety monitoring board after data collection has been completed for 50% of the enrollment.

Inclusion Criteria:

• Age > 18 years and < 70 years
• Patients with native MDP who underwent ERCP

Exclusion Criteria:

• Prior surgery in upper GI tract
• Prior history of endoscopic sphincterotomy
• Prior history of MDP treatment
• Known or suspected obstruction of upper GI tract
• Patients in poor condition who may not be suitable for Ca-EGD or duodenoscope
• Pregnancy or lactic women
• Inability to give informed consent