The investigators will prospectively collect patient and procedure-related data in an observational study in order to detect patient and procedure-related risk factors for poor outcome (i.e. technical failure of the procedure; procedure-related complications).

Data will be prospectively reported using standard report forms and patients will be followed up to 30 days to detect late-onset complications.

This is an investigator-driven, prospective multicenter trial which analyzes the impact of trainee participation on procedure-related outcome (technical success and procedure-related complications).

All ERCPs in the participating centers will be documented using a standard report form which will require the attending endoscopist to provide data relating to the patient (age, gender, diagnosis, bilirubin levels) and the procedure (including but not limited to the indication, technical aspects including cannulation technique, time to cannulation, degree of trainee involvement - where appropriate, procedure-related adverse events and their outcome).

Because teaching ERCP is not yet a standardized procedure, we aim to assemble a large database, stemming from the experience of several teaching centers in order to identify the main patient and operator-related factors which might influence the outcome of the procedure.

Inclusion Criteria:

• all patients undergoing ERCP with attempted cannulation of either the major or minor papilla

Exclusion Criteria:

• refusal to sign the informed consent

all consecutive patients undergoing ERCP in an endoscopy training program setting