Evaluation of Placental Membrane Swabs in the Diagnosis of Intrauterine Infections

Aims: To evaluate the performance of bacterial culture of placental swabs for the diagnosis of intrauterine infections in preterm and term infants. Methods: A total of 1438 placentas were examined after preterm and term deliveries and the results were compared with neonatal surface swabs and blood cultures, with respect to the diagnosis of perinatal infection. Swabs were inserted between the cotyledones into the space between placenta and amnion, or obtained from the membranes after separation of the amnion from the chorion. Results: Sixty-one of 1438 (4.2%) cultures of placental swabs were positive including 21 Bacteroides species, 13 Eschericia coli (E. coli), 11 group B streptococcus (GBS), 4 Enterococcus faecalis, and 12 other species. Seventeen of the 61 neonates with positive placental cultures showed clinical signs of infection or sepsis (5 E. coli, 6 GBS, 2 Enterococcus faecalis, 1 Klebsiella pneumoniae, 1 Staphylococcus aureus, 1 Candida albicans, 1 Gardnerella vaginalis), but only 4 of these neonates had a positive blood culture. 123 of 1438 (8.6%) placental swabs were contaminated. Sensitivity and positive predictive value of placental swabs for the diagnosis of neonatal infection were 62.5% and 38.5% for E. coli and 60% and 54.5% for GBS, respectively. Conclusion: Placental swabs appear to be helpful for the retrospective identification of the causative bacteria in case of chorioamnionitis with or without neonatal infection. However, the performance of placental swabs should be improved by developing a standardized technique.