Effect of Glyceryl Trinitrate Ointment on Pain Control after Hemorrhoidectomy: A Meta-analysis of Randomized Controlled Trials

Background: Hemorrhoidectomy is associated with postoperative pain and prolonged wound healing. Glyceryl trinitrate has been shown to decrease muscle spasm and increase anodermal blood flow. A meta-analysis of randomized controlled trials was conducted to evaluate the efficacy of topical glyceryl trinitrate application in pain relief after hemorrhoidectomy. Methods: PubMed, EMBASE, Cochrane Library, Scopus, and ClinicalTrials.gov registries were searched for studies published before August 2015. Individual effect sizes were standardized, and a meta-analysis was conducted to calculate a pooled effect size using random effects models. Pain was assessed using a visual analog scale on days 1, 3, 7, and 14 after operation. Secondary outcomes included time taken to resume routine activities, wound healing at 3 weeks after operation, complication, and headache incidence. Results: A total of 12 trials with 1095 patients were reviewed. Significant pain reduction was observed on days 1, 3, 7, and 14 after hemorrhoidectomy in the glyceryl trinitrate groups. Glyceryl trinitrate-treated patients appeared to resume routine activities earlier than those in the control group (weight mean difference -7.52; 95 % confidence interval: 16.13-1.08). The wound healing rates 3 weeks after operation were significant higher in the glyceryl trinitrate-treated groups than in the control group (risk ratio 1.79; 95 % confidence interval: 1.38-2.33). However, the incidence of headache significantly increased in the glyceryl trinitrate group (risk ratio 3.68; 95 % confidence interval: 1.62-8.34). Conclusion: Topical application of glyceryl trinitrate effectively relieves pain and promotes wound healing after hemorrhoidectomy; however, the substantial headache incidence may limit extensive application.