Efficacy of crystal violet for identifying the distal end in esophageal submucosal tunnel resection

Background Endoscopic submucosal tunnel dissection (ESTD) has recently been an effective procedure for resecting large early esophageal neoplasm. However, excessive dissection beyond the distal limit may occur because the prepared distal end often cannot be distinguished through the tunnel. This study aimed to assess the efficacy and safety of a novel crystal violet navigation (CVN) for identifying the distal end. Material and methods In the observational case series study, all 22 patients who underwent esophageal ESTD using the CVN were included. When setting the distal end, the distal incision line was dyed purple using a crystal violet solution. The rates of purple color identified via the tunnel, successful tunnel penetration without extra dissection, en bloc and curative resection, procedure time for ESTD and CVN, and procedure-associated complications were evaluated. Results The rates of purple color and successful tunnel penetration were both 100%. En bloc and curative resection were 100%, and 86%, respectively. The mean total procedure time was 103.9 ± 46.2 (mean ± SD) minutes, while the mean time for the CVN was 14.1 ± 3.44 s. No complications were observed. Conclusions The simple CVN method can be a navigation tool for identifying the distal end during the ESTD procedure.