All patients referred for the evaluation of indeterminate strictures or removal of difficult stones will be eligible for enrollment in the consortium. The PI or study coordinator will meet with the patient and discuss the study, its objectives, and obligations with each patient. After full disclosure, informed consent will be obtained.
Upon consent, basic demographics and data from prior procedures (when available) will be recorded. An endoscopist proficient in ERCP, with expertise in cholangioscopy, will perform the procedures using the Spyglass DS system with its associated components including biopsy forceps (SpyBiteTM) and other accessories as necessary. Procedure time, visual findings, number of biopsies taken, pathology, stone location, stone size, and method of stone clearance and adverse events will be recorded on data collection forms and transferred into a centralized password protected database. All patients will be followed for 6-12 months or surgery (stricture cohort) to assess accuracy or stone recurrence rates.