Objective: The purpose of the present study was to compare early post-operative complications and length of hospital stay of hemorrhoidectomy patients between those who had and had not received metronidazole perioperatively. 
Research design: Retrospective, matched pair case-control study.
Material and Method: Medical records of all hemorrhoidal patients hospitalized between January 2000 and December 2005 were reviewed. Hemorrhoidectomy patients who had and had not received metronidazole perioperatively during this period were matched based on demographic data. Demographic data including bodyweight and number of hemorrhoidectomies of both groups were collected. Length of hospital stay and immediate post-operative complications (bleeding, urinary retention, and wound dehiscence at 2nd and 4th week), the total dosages of pethidine, acetaminophen, and NSAIDs were analyzed and compared by the McNemar and the Wilcoxon Signed Rank Test.
Results: Of 1,184 patients who completed the follow-up protocol, 88 patients (male: female = 31:57) who had received metronidazole could be matched by gender, age, NSAIDs used, number of hemorrhoids resected and operation in the same period with 88 patients (male:female = 31:57) who had not. There were six (6.8%) and seven (8%) patients with urinary retention in the metronidazole group and non-antibiotic group respectively. One patient in each group (1.1%) experienced bleeding that ceased spontaneously. The length of hospital stay was 1.14 + 0.35 (ranged 1-2) and 1.11 + 0.35 (ranged 1-3) days in the metronidazole and the nonantibiotic group respectively, showing no significant difference (p = 0.683). There was no significant difference in the total dosages of pethidine given postoperatively, which was 1.06 + 0.83 and 1.03 + 0.78 mg/kg in the metronidazole and the non-antibiotic group respectively (p = 0.747). At the 2nd week, there were two wound dehiscences (2.25%) in each group. At the 4th week, no more new wound dehiscence was detected and all were completely healed without stricture.
Conclusion: There was no benefit of metronidazole on closed hemorrhoidectomy with respect to post-operative complications, length of hospital stay, and total analgesics used.

Keywords: Hemorrhoid, Hemorrhoidectomy, Wound dehiscence, Metronidazole