Benefit of pronase in image quality during EUS

Background: EUS is useful for diagnosis of GI disease. However, artifacts caused by gastric mucus may worsen visibility during EUS. Objective: To investigate the efficacy of premedication with pronase, the proteolytic enzyme, for improving imaging during EUS. Design: Blinded, randomized, prospective study. Setting: Tertiary-care referral center. Patients: This study involved 183 patients scheduled for EUS. Intervention: Patients were assigned to oral premedication with saline solution (group A), pronase and bicarbonate (group B), or pronase, bicarbonate, and simethicone (group C). Either conventional EUS or high-frequency catheter EUS (HFUS) was selected. Gastric cavity and gastric mucosal surface obscurity grades were assessed by using visibility scores from ultrasonographic images of each patient. Main Outcome Measurements: Means of visibility scores and proportion of images with better visibility scores of the gastric cavity and gastric mucosal surface. Lower scores indicate better visibility of the gastric mucosal surface and fewer artifacts within the gastric cavity on conventional EUS and HFUS. Results: Group B had significantly lower mean gastric cavity and gastric mucosal surface visibility scores than did groups A and C in both conventional EUS and HFUS. Group B also had a high proportion of images that had better gastric cavity and gastric mucosal surface visibility scores than did the other two groups in conventional EUS and HFUS. Limitations: Small number of patients and no assessment of the amount of mucus before oral premedication. Conclusion: Premedication for conventional EUS and HFUS by using a mixture of pronase and bicarbonate seems to decrease the number of gastric wall and lumen hyperechoic artifacts observed in patients given either saline solution or pronase/bicarbonate/simethicone. (Gastrointest Endosc 2011;74:1230-7.)