Pre‐medication with pronase reduces artefacts during endoscopic ultrasonography

Summary Background : Gastric mucus usually induces artefacts during endoscopic ultrasonography. Aim : To investigate the effectiveness of pre‐medication with the proteolytic enzyme, pronase, before endoscopic ultrasonography. Methods : Out‐patients scheduled for endoscopic ultrasonography were randomly assigned to oral pre‐medication with the anti‐foam agent, dimethylpolysiloxane, alone (treatment A; n = 29), with dimethylpolysiloxane plus sodium bicarbonate (treatment B; n = 29) or with dimethylpolysiloxane, sodium bicarbonate and pronase (treatment C; n = 29). All drinks were given about 10 min before the start of the procedure. After insertion of the endoscope, endoscopists recorded visibility scores before the procedure, imaging scores at endoscopic ultrasonography and the numbers of high‐echo spots in the gastric cavity and on the gastric wall surface after the procedure. Results : Pre‐medication with pronase (treatment C) significantly reduced (both at P < 0.05) the visibility score (score 4, 46%) in comparison with that obtained for pre‐medication without pronase (10% for both treatments A and B). Treatment with pronase significantly reduced (both at P < 0.05) the endoscopic ultrasonography score in the gastric cavity (score 4, 34%) in comparison with that found for treatments A (7%) and B (0%). It also significantly reduced ( P < 0.05) the endoscopic ultrasonography score on the gastric wall surface (score 4, 14%) in comparison with that observed for treatment A (3%). The numbers of high‐echo spots in the gastric cavity and on the gastric wall surface were significantly less (both at P < 0.001) for pre‐medication with pronase (treatment C) than for pre‐medication with treatments A and B. There were no complications associated with the solutions. Conclusions : Pre‐treatment with pronase reduced the artefacts during endoscopic ultrasonography.