Metronidazole prophylaxis in elective first trimester abortion.

In a double-blind controlled trial, the efficacy of prophylactic metronidazole in elective first trimester abortions was assessed. Of 119 randomized women, 100 followed the protocol. Fifty-one women received 400 mg metronidazole one hour before and again four and eight hours after abortion; 49 women received a placebo. In the placebo group 20.4% contracted postabortal genital infection compared with 3.9% in the metronidazole group (P less than .025). Of 25 women with a positive history of pelvic inflammatory disease, six contracted postabortal infection, which was a significantly increased frequency compared with women without previous episodes of pelvic inflammatory disease (P less than .05). The administration of prophylaxis, however, did not significantly influence the frequency. The number of hospital days was not significantly lower in the prophylaxis group (P greater than .05). The total amount of metronidazole prescribed in the study group was significantly larger than in the placebo group (P less than .05), whereas the amount of ampicillin/pivampicillin prescribed in the placebo group was significantly larger (P less than .05). The difference between the penicillin doses given in the treatment and placebo groups was not significant (P greater than .1).