Physical effect of various submucosal elevation solutions for colorectal endoscopic procedure: Measuring the vertical-to-horizontal ratio.

im: Submucosal elevation solution is an essential element used in endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) for colorectal lesions. Therefore, it is important to select a suitable solution for the endoscopic procedure. The aim of the present study was to examine the real time vertical-to-horizontal (V-H) ratio physical effect of submucosal elevation solution during colorectal EMR. Methods: This was a prospective randomized study carried out at an endoscopy centre in a Hong Kong hospital. A total of 10 patients with 15 colorectal adenoma requiring EMR were recruited. The studied submucosal elevation solutions included normal saline, glycerol and hyaluronic acid. Before EMR, 3 mL of these solutions were injected in the submucosal space, one solution at a time. The vertical and horizontal length of the elevated submucosal space was measured by miniprobe ultrasound. V-H ratios of different solutions were calculated and compared. Vertical distance, horizontal distance and V-H ratio of the submucosal space after injection of the submucosal elevation agents were measured. Results: The mean size of lesions was 14 mm (range 10-20). Glycerol and hyaluronic acid had a significant higher V-H ratio than normal saline; the V-H ratio of normal saline, glycerol and hyaluronic Acid were 0.29, 0.53 and 0.50, respectively. Limitations: The exact volume of the injection was not certain, and the time between the injection and endoscopic ultrasound assessment was variable. These limitations were overcome by calculating the V-H ratio. Conclusion: Glycerol and hyaluronic acid have a higher V-H ratio, which makes them good submucosal elevation solutions. [ABSTRACT FROM AUTHOR]