Perinatal outcomes according to the aerobic vaginitis in patients with preterm premature rupture of membranes

Aerobic vaginitis (AV) is one of the normal vaginal flora disturbances, characterized by abnormal vaginal flora with the disruption of lactobacillus and the presence of aerobic microflora, and vaginal inflammation. The effect of AV on perinatal outcomes in patients with preterm premature rupture of membranes (pPROM) has not been yet fully investigated. The objective of this study was to address this issue. A retrospective cohort study was conducted in singleton pregnant women (N=240) who were admitted due to pPROM (≤34 weeks of gestation) in a single tertiary hospital between 2007 and 2017 and who underwent the Gram-stain and culture for bacteria in vaginal swab samples. The vaginal condition associated with aerobic vaginitis (VC-AV) was defined when there were one or more findings among the following: 1) the presence of aerobic bacteria by cultivation, 2) lack of lactobacillus, and 3) relatively abundant leukocytes compared to the epithelial cells on Gram-stained vaginal smears. During the study period, VC-AV was observed in 197 patients (82.1%). The presence of VC-AV was associated with a higher rate of histological chorioamnionitis (p< 0.05). Patients with VC-AV had a lower mean gestational age at delivery and higher rates of preterm delivery (PTD) and spontaneous PTD (≤ 32 weeks) than those without (p< 0.05, for all). Adverse neonatal outcomes such as neonatal intensive care unit admission and neonatal respiratory distress syndrome were associated with the presence of VC-AV (p< 0.05, for all). When the study population was classified into 3 groups according to the severity of VC-AV (intermediate: 1 or 2 findings; severe: all 3 findings), additional findings were discovered that the rates of elevated maternal serum C-reactive protein concentration (>8 mg/dL), spontaneous PTD (≤34 weeks), and bronchopulmonary dysplasia and were increasing as AV-VC was more severe. VC-AV in preterm PROM was related to maternal and placental inflammation and adverse perinatal outcomes. These data can give us an insight into the importance of AV in patients with preterm PROM.