The purpose of this study is to demonstrate the feasibility and validity of a previously developed peroral cholangioscopy (POC) convolutional neural network (CNN) to determine the etiology of biliary strictures when used in real-time.

Inclusion Criteria:

• Age ≥ 18 years old
• Anticipation that patient may undergo POC during an endoscopic retrograde cholangioscopy
• Pregnant patients can be included in the study. Use of the POC-CNN does not convey any new risk to the patient nor fetus.
• Non-English speaking subjects will be included in the study. Consent for the procedure itself is always done with the assistance of an interpreter via telephone or video. Use of the POC-CNN will be discussed with all patients via this interpreter during the procedure consent.

Exclusion Criteria:

• Age <18 years old
• No indication that cholangioscopy will be performed during endoscopic retrograde cholangiopancreatography (ERCP)
• Prisoner

Patients with biliary strictures who are undergoing peroral cholangioscopy (POC) during endoscopic retrograde cholangiopancreatography (ERCP) for the evaluation of a biliary strictures will be identified via review of procedure listings at Mayo Clinic Rochester, Minnesota.