This study will test two different methods for processing biopsy specimens taken from the bile duct. Patient;s who are asked to participate int his study have a stricture in the bile duct that needs a single operator cholangioscopy-guided biopsies during endoscopic retrograde cholangiopancreatography (ERCP) so that a diagnosis can be made. Standard of care includes performing single operator cholangioscopy-guided biopsies in the bile duct and sending the tissue to the lab for testing to make a diagnosis. Using this method the investigators can establish a diagnosis only about 50% of the time. The investigators believe that if a cytopathologist is available in the endoscopy suite during the procedure to evaluate the biopsy specimens onsite, the investigators can improve the diagnostic accuracy. The purpose of this study is to compare two methods for processing biopsies obtained from the bile duct (Onsite vs. Offsite).

The diagnostic accuracy rate of single operator cholangioscopy-guided biopsy is only 50%. This translates to the need for performing repeat procedures to establish a diagnosis and therefore delays patient treatment. The biopsy specimen obtained at cholangioscopy are usually processed offsite in the pathology lab. We believe that if a pathologist can assess the tissue sample during the procedure itself (onsite) and provide feedback, the diagnostic accuracy rate will improve. This translates to better (faster) diagnosis and early treatment. Therefore, we will be comparing onsite versus offsite evaluation of bile duct biopsy specimens to determine which method yields a better diagnosis.

Inclusion Criteria:

• Age > 18 years
• Suspected biliary stricture

Exclusion Criteria:

• Age < 18 years
• Pregnancy
• Altered surgical anatomy
• Irreversible elevation in INR > 1.5 or low platelet count < 50,000