Predictive Value of Amniotic-Membrane Cultures for the Development of Postcesarean

This study assesses (1) the relationship between the bacteriology of amniotic-membrane cultures (AMCs) obtained at the time of primary cesarean section and the subsequent postoperative course of afebrile, laboring patients whose membranes ruptured >4 hr before delivery and (2) the impact of perioperative antibiotics on this relationship. Therapy with perioperative antibiotics was begun after the cord was clamped and the membrane specimen was obtained for culture. Specimens for AMC were obtained from 127 patients; 62 received placebo and 65 received perioperative antibiotics. In spite of the homogeneity of the patients' clinical risk factors, their AMCs demonstrated considerable variation in the degree of bacterial contamination present at the time of cesarean section. The presence of no growth or of low-virulence isolates only in the AMC usually was associated with a benign postoperative course, and therapy with perioperative antibiotics did not significantly decrease the incidence of endometritis associated with these AMC patterns. On the other hand, the presence of a mixture of high- and low-virulence organisms in the AMC or of high-virulence anaerobes only-more specifically, gramnegative anaerobes-was predictive of subsequent postcesarean endometritis only for patients who did not receive perioperative antibiotics, and therapy significantly decreased the incidence of endometritis associated with these AMC patterns. In conclusion, the correlation between specific bacteriologic patterns found in the AMC and the subsequent development of endometritis for patients who did not receive prophylactic antibiotics was better than the correlation based on clinical risk factors alone.