Visibility of the bleeding point in acute rectal hemorrhagic ulcer using red dichromatic imaging: A case report

BACKGROUND: Red dichromatic imaging (RDI) is a novel image-enhanced endoscopy expected to improve the visibility of the bleeding point. However, it has not been thoroughly investigated. CASE SUMMARY: A 91-year-old man developed a sudden massive hematochezia and underwent emergent colonoscopy. An ulcer with pulsatile bleeding was found on the lower rectum. Due to massive bleeding, the exact location of the bleeding point was not easy to detect with white light imaging (WLI). Upon switching to RDI, the bleeding point appeared in deeper yellow compared to the surrounding blood. Thus, RDI enabled us for easier recognition of the bleeding point, and hemostasis was achieved successfully. Furthermore, we reviewed endoscopic images and evaluated the color difference between the bleeding point and surrounding blood for WLI and RDI. In our case, the color difference of RDI was greater than that of WLI (9. 75 vs 6. 61), and RDI showed a better distinguished bleeding point from the surrounding blood. CONCLUSION: RDI may improve visualization of the bleeding point by providing better contrast in color difference relative to surrounding blood.