Efficacy of submucosal bupivacaine injection for pain relief after endoscopic submucosal dissection A multicenter, prospective, randomized controlled, and double-blind trial

Background and aim: Although abdominal pain is a common adverse event related to endoscopic submucosal dissection (ESD), it can be sometimes underestimated by endoscopists. There are some endoscopic interventions available for the prevention of post-ESD pain, but their efficacy has not been established. We investigated whether a submucosal injection of bupivacaine (BP) can reduce procedure-related abdominal pain compared with the standard method. Methods: We performed a multicenter, double-blinded, randomized controlled trial of 86 adult patients referred for ESD as treatment for gastric neoplasms. Patients were randomly assigned to either the BP submucosal or conventional solution group. Questionnaires were collected when the study began (baseline) and immediately after ESD, as well as at 6, 12, and 24-hours post-operatively. The primary outcome was indicated by the visual analog scale (VAS) evaluated at 6 hours after procedure. Results: There were no significant differences in primary outcomes between groups and among all time points (immediately, 12, and 24 hours after ESD). The VAS and short-form McGill pain (SF-MP) scores were higher immediately after ESD than at 6, 12, or 24 hours post-operatively. The incidence of abdominal pain immediately after ESD was 94.0% (78/83) for all patients of both groups, and there was no significant difference between the 2 groups in the rate of abdominal pain immediately after ESD (BP group 37/40 [92.5%] versus non-BP group 41/43 [95.3%], P=.934). In univariable and multivariable analyses, BP did not have protective effect on post-ESD abdominal pain. Conclusions: Submucosal BP injection does not promote pain relief or mitigate the effects of post-ESD abdominal pain.