Identification of bleeding points after bile duct biopsy using red dichromatic imaging during peroral cholangioscopy: A case report.

Red dichromatic imaging is a new image-enhancement technology that clarifies the differences in blood concentrations and improves the visibility of the bleeding point. A 71-year-old man was presented with a common bile duct stone, which was completely removed using electrohydraulic shock wave lithotripsy with peroral cholangioscopy. During peroral cholangioscopy, a nodular lesion was found at the confluence of the cystic duct, and a forceps biopsy was performed. It was difficult to confirm the bleeding point using white-light imaging because of the pooling of blood. After switching to red dichromatic imaging mode 2 and washing the bile duct with saline solution, the bleeding point was observed in darker yellow than the surrounding blood, allowing the identification of the bleeding point. Red dichromatic imaging can be used in the future to maintain hemostasis during peroral cholangioscopy.