The role of direct peroral cholangioscopy using an ultraslim endoscope for biliary lesions: indications, limitations, and complications.

Advantages of direct peroral cholangioscopy (POC) using an ultraslim endoscope include use of conventional endoscopy equipment, operation by a single endoscopist, and superior image quality of the biliary tree with easy application of enhanced endoscopy and a large working channel. The major diagnostic indications of this system are an evaluation of biliary strictures, filling defects, or unclear findings on cholangiogram or other imaging studies. Therapeutic application using a direct POC system can be broadened by a larger working channel. However, direct POC is difficult to apply in patients with a narrow diameter bile duct, far distal common bile duct lesion, or failed anchoring of the scope with accessories. An air embolism is a rare complication of direct POC but can be a fatal problem. Cholangitis can also occur during or after the procedure. Use of a CO2 system instead of room air during the POC procedure and administration of antibiotics before and after the procedure are strongly recommended. Continuous development of specialized endoscopes and accessories is expected to facilitate the diagnostic and therapeutic roles of direct POC.