Single-dose ampicillin for cesarean section prophylaxis.

A single 2-g dose of ampicillin or a placebo identical in appearance was administered intravenously in a randomized, prospective, double-blind manner to 71 patients undergoing cesarean section. The solutions were given either on call to the operating room or during the intraoperative period. Postoperative morbidity from infection occurred in 59.4% of patients receiving placebo and in 14.7% of those receiving ampicillin (P less than .0001). In those individuals undergoing primary cesarean section the incidence of infection with placebo was 65% and with ampicillin 6.3% (P less than .0004). In patients undergoing repeat cesarean section the incidence was 53% in the placebo group and 22% in the treatment group (P greater than .05). There were no differences in the effectiveness of the drug whether given preoperatively or intraoperatively. Serious infections and wound infections were not encountered in patients receiving ampicillin.