Metronidazole following excisional haemorrhoidectomy: a systematic review and meta-analysis

Background: Post-operative pain is a major issue following excisional haemorrhoidectomy. Although metronidazole by both oral and topical administration routes has been shown to reduce pain after haemorrhoidectomy, its use remains a contentious issue. This systematic review and meta-analysis aims to investigate the effect of metronidazole on post-operative pain after excisional haemorrhoidectomy. Methods: A systematic review of the literature was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Randomized controlled trials (RCTs) published in PubMed/MEDLINE, EMBASE, CENTRAL and CINAHL, from inception to December 2016 were retrieved. The primary outcome investigated was post-operative pain reported as visual analogue score (VAS). Secondary outcomes were analgesia use, complications and time to return to normal activity. Metaanalysis was performed using Review Manager version 5.3 software. Results: Nine randomized controlled trials including 523 patients were included in the final analysis. Five studies used oral administration and four used topical. Meta-analysis showed that post-operative VAS of patients receiving metronidazole by either route was significantly less than those in comparison groups. VAS means decreased at all the time points for both oral and topical metronidazole. Topical and oral routes of administration were not compared in any study. There was no increase in complication rates and return to normal activity was significantly earlier for patients receiving metronidazole (-4.49 days; 95% confidence interval [-7.70, -1.28]; P = 0.006). Conclusions: Both topical and oral metronidazole reduce post-operative pain without an increase in complication rates and result in an earlier return to normal activity. Further work is required to determine which the optimum route of administration is.