Current status of peroral cholangioscopy in biliary tract diseases.

Peroral cholangioscopy (POC) is an important tool for the management of a selected group of biliary diseases. Because of its direct visualization, POC allows targeted diagnostic and therapeutic procedures. POC can be performed using a dedicated cholangioscope that is advanced through the accessory channel of a duodenoscope or via the insertion of a small-diameter endoscope directly into the bile duct. POC was first described in the 1970s, but the use of earlier generation devices was substantially limited by the cumbersome equipment setup and high repair costs. For nearly ten years, several technical improvements, including the single-operator system, high-quality images, the development of dedicated accessories and the increased size of the working channel, have led to increased diagnostic accuracy, thus assisting in the differentiation of benign and malignant intraductal lesions, targeting biopsies and the precise delineation of intraductal tumor spread before surgery. Furthermore, lithotripsy of difficult bile duct stones, ablative therapies for biliary malignancies and direct biliary drainage can be performed under POC control. Recent developments of new types of conventional POCs allow feasible, safe and effective procedures at reasonable costs. In the current review, we provide an updated overview of POC, focusing our attention on the main current clinical applications and on areas for future research.