Key to successful Cold Snare Polypectomy with New Technology: EDOF and RDI

In recent years, Cold Snare Polypectomy (CSP) has been widely adopted as a simple, minimally invasive, and safe procedure for removing small colorectal polyps. However, because the resection depth in CSP is shallower compared to methods like EMR, its indication is currently limited to adenomas. Therefore, accurate endoscopic diagnosis prior to CSP is crucial.

The Japanese guidelines for colorectal cold polypectomy recommend that “the indications should be limited to lesions smaller than 10 mm that are preoperatively diagnosed as adenoma and which can be resected completely en bloc¹ “. Furthermore, the commentary states that “the use of image-enhanced endoscopy with magnification is recommended for a highly accurate preoperative diagnosis of colorectal lesion prior to cold polypectomy ².” This is because, even in lesions under 10 mm, the rate of intramucosal cancer is 0.4% in lesions less than 5 mm in diameter, and 3.4% in lesions between 5 mm and 10 mm, meaning that relying solely on size for CSP indications may lead to residual tumor risk³.

The biggest drawback that often leads to magnified observation being avoided is the complexity of focusing. The newly installed Extended Depth of Field (EDOF) function on the CF-EZ1500D system overcomes this by simultaneously acquiring and synthesizing near-focus and far-focus images, resulting in a wider depth of field. This technology reduces the complexity of focusing associated with conventional magnified observation, facilitates high-magnification observation in near focus mode, and enables stable, easy magnified observation for any physicians. The conventional CF-HQ290 scope allowed for close observation up to 9 mm in normal focus mode, and magnified observation between 4 mm and 9 mm in near focus mode. The CF-EZ1500D scope allows for close observation up to 3 mm even in normal focus mode, and further utilizes the near focus mode to enable magnified observation between 1.5 mm and 5.5 mm.

The points to note immediately after CSP are bleeding and residual tissue. Since CSP does not involve electrocautery, there is no so-called “burning effect.” Therefore, when capturing the lesion with the snare, it is important to include a margin of surrounding non-neoplastic mucosa. After CSP, re- examine the mucosal defect margin using NBI + Near focus to check for any residual tissue. Again, the EDOF function makes focusing and magnified observation significantly easier here.
While pulsatile or arterial bleeding is rare after CSP, minor oozing is almost always present. Applying the water jet to the post-CSP mucosal defect helps achieve a tamponade state for pressure-based hemostasis. Red Dichromatic Imaging (RDI) is a wavelength selection technology that enhances the visibility of deep vessels and bleeding points, making it useful for identifying bleeding sites and evaluating hemostasis. Even when a bleeding point is difficult to confirm, switching to RDI facilitates its identification, making hemostatic procedures and confirmation of successful hemostasis much easier and highly useful.

The newly installed EDOF function on the CF-EZ1500D scope dramatically simplifies conventional magnified observation and enables the acquisition of very clear magnified images that are in focus over a wide range. This function allows for accurate determination of the indication during the pre-CSP diagnostic phase and is also highly effective in checking for residual tissue after resection. Furthermore, the combination with RDI facilitates the identification of bleeding points and confirmation of hemostasis after CSP, which we believe will significantly contribute to the treatment of colorectal polyps, including CSP.