Predictors of antibiotic prophylactic failure in post-cesarean endometritis.

Despite the use of prophylactic antibiotics, endometritis occurs in 1-31% of patients after cesarean delivery. We sought to identify predictors of prophylactic antibiotic failure. In a retrospective review of 1800 cesarean deliveries, 766 patients had either ampicillin or cefazolin prophylaxis; 240 (31.3%) developed endometritis. Stepwise logistic regression identified the number of vaginal examinations (P less than .001), nulliparity (P = .001), low gestational age (P = .033), and cefazolin use (P = .002) as predictors of endometritis. One in two women with six or more vaginal examinations before cesarean delivery will have prophylactic failure. In preterm gestations (N = 177), the number of vaginal examinations was the single predictor of prophylactic antibiotic failure (P = .002). The number of vaginal examinations can be used to design new strategies to prevent a high rate of prophylactic failure.