Prophylactic metronidazole in prevention of infection after appendicectomy: report of a double-blind trial.

A randomized double-blind trial was carried out in 405 patients undergoing appendicectomy to assess the prophylactic effect of metronidazole in postoperative infection. 200 patients received metronidazole and 206 received placebo. Preoperatively all patients were given an intravenous infusion of metronidazole or placebo. In patients with a perforated appendix postoperative medication was continued with suppositories containing either metronidazole or a placebo plus additional chemotherapy with penicillin and streptomycin. The infection rate in patients with a non-perforated appendix was 8% in the placebo group and 1% among those receiving metronidazole. In patients with a perforated appendix, the corresponding figures were 45% and 0%. These differences are statistically significant. B. fragilis and E. coli were isolated from the majority of the postoperative infections;. most often in a mixed culture. Both intravenous and rectal administration of metronidazole gave adequate blood levels. No side effects were encountered.