L-Menthol for Gastrointestinal Endoscopy: A Systematic Review and Meta-Analysis

INTRODUCTION: In randomized controlled trials, L-menthol inhibits gastrointestinal peristalsis during endoscopy. Our goal was to quantitatively synthesize the available evidence to evaluate the efficacy and safety of L-menthol for gastrointestinal endoscopy. METHODS: We comprehensively searched for relevant studies published up to January 2020 in PubMed, EMBASE, Web of Science, and Cochrane Library. The main outcomes consisted of the proportion of no peristalsis, proportion of no or mild peristalsis, adenoma detection rate, and adverse events. RESULTS: Eight randomized controlled trials analyzing 1,366 subjects were included. According to the pooled data, L-menthol significantly improved the proportion of no peristalsis (odds ratio [OR] = 6.51, 95% confidence interval [CI] = 4.94-8.57, P < 0.00001), and the proportion of no or mild peristalsis (OR = 7.89, 95% CI = 5.03-12.39, P < 0.00001) compared with the placebo, whereas it was not associated with an improvement in the adenoma detection rate (OR = 1.03, 95% CI = 0.54-1.99, P = 0.92). Adverse events did not differ significantly between the 2 groups (OR = 1.40, 95% CI = 0.75-2.59, P = 0.29). DISCUSSION: The findings of this study support the use of L-menthol to suppress gastrointestinal peristalsis during endoscopic procedure.