Patients who have lab tests, positive imaging tests or obstructions will usually have a test called ERCP (Endoscopic Retrograde Cholangiopancreatogram) to take biopsies and enlarge bile ducts or opening bile ducts with stents. Patients usually have cells in the bile ducts removed and analyzed, but there are not studies to show how sensitive this may be to determine if the cells are cancer or pre-cancerous. A new scope with a system using light filters called Narrow Band Imaging (NBI) may help detect cancer and pre-cancer more often and at an earlier stage.