Efficacy of hyaluronic acid in endoscopic mucosal resection of colorectal tumors.

Background and Aim: Endoscopic mucosal resection (EMR) is the standard procedure for colorectal tumors. High mucosal elevation by submucosal injection is important for definite en bloc resection and the prevention of perforation. Hyaluronic acid (HA) is a reportedly useful injection solution for high and long-lasting mucosal elevation, but the ideal HA concentration for optimization of mucosal elevation maintenance, injection pres- sure, and cost is unknown. In the present study, we assessed the appropriate concentration of HA for EMR. Methods: A resected porcine colon and esophagus were used. The injection solutions examined were 0.9% normal saline (NS) and four concentrations of an 800-KDa HA preparation (0.4%, 0.2%, 0.13%, and 0.1%). Each solution (2 mL) was injected into the submucosa; injection pressure was calculated, and elevation was measured. The durations of mucosal elevation and EMR were additionally assessed in the living minipig colon. Results: In the resected porcine colon, the mucosal elevation was measured 0, 2, 4, and 6 min after the submucosal injection.All concentrations of HAsolution maintained greater mucosal elevation at all times than NS (P < 0.05).An almost similar result was obtained in the resected porcine esophagus. The injection pressure correlated with the HA concentra- tion. In the living minipig colon, mucosal elevation diminished 2 min after the submucosal injection with NS, but was maintained 2 min after injection with 0.4%, 0.2%, and 0.13% HA. The average duration of EMR was 139 s. Conclusions: Mucosal elevation by HAwas greater than that by NS in resected and living animal models. We recommend 0.13% HA for maintaining mucosal elevation, injection pressure, and cost.