Residual Amniotic Fluid Volume in Preterm Rupture of Membranes: Association with Fetal Presentation and Incidence of Clinical and Histologic Evidence of Infection

ABSTRACT

The objective of this study was assess whether residual amniotic fluid volume (AFV) following premature rupture of the membranes (PROM) is associated with fetal presentation, or the prevalence of either clinical or histologic infection in patients delivering below 32 weeks' gestation. From an established database of 465 deliveries below 32 weeks' gestation, patients with singleton, nonanomalous fetuses with AFV assessment within 24 hours of delivery were studied (n = 146). Fetal presentation was confirmed by ultrasound identifying 46 breech and 100 vertex-presenting fetuses. Premature rupture of the membranes was diagnosed by sterile speculum examination. Clinical chorioamnionitis was diagnosed by previously published criteria. Histopathology examination of the extraplacental amnion and the umbilical cord were performed by a single pathologist blinded to clinical data. Outcome variables evaluated: rupture-to-delivery interval, gestational age at delivery, neonatal morbidity parameters (1- and 5-min Apgar scores <5 and 7, respectively; incidence of respiratory distress syndrome; bronchopulmonary dysplasia; retinopathy of prematurity; neonatal sepsis; intraventricular hemorrhage; days of ventilation; and hospitalization), and placental histologic parameters of maternal and/or fetal acute inflammation. Statistical analysis included contingency tables and analysis of variance with p <.05 considered significant, after corrections for multiple comparisons when appropriate. Residual AF volume following PROM was significantly lower in breech compared with vertex presentation (AFV = 0 in 20 vs. 34; AFV = 1 in 19 vs. 27; AFV = 2 in 7 vs. 39, respectively, p = .014). No significant difference was noted in the rupture-to-delivery interval, gestational age at delivery, neonatal morbidity parameters, or histologic evidence of maternal and/or fetal acute inflammation (50% vs. 42%, p >.2) between gestations with breech or vertex presentations. The incidence of clinical chorioamnionitis was significantly lower in breech compared with vertex presention (40% vs. 60%, p <.05). We conclude that following PROM below 32 weeks' gestation, in breech-presenting fetuses, the residual AFV and incidence of clinical chorioamnionitis are significantly decreased compared with vertex-presenting fetuses.

Keywords

Premature rupture of membranes - prematurity - amniotic fluid volume - fetal presentation - chorioamnionitis - ultrasonography