The frequency and clinical significance of intra-amniotic infection and/or inflammation in women with placenta previa and vaginal bleeding: an unexpected observation

Abstract

Objective: Idiopathic vaginal bleeding, a common complication of pregnancy, increases the risk of small-for-gestational age (SGA) neonate, preeclampsia and preterm delivery and can be the only clinical manifestation of intra-amniotic infection and/or inflammation (IAI). Placenta previa is thought to be protective against ascending intrauterine infection, yet an excess of histologic chorioamnionitis has been reported in this condition. The aim of this study was to determine the frequency and clinical significance of IAI in women with placenta previa and vaginal bleeding in the absence of preterm labor.

Study design: A retrospective cohort study including 35 women with placenta previa and vaginal bleeding <37 weeks of gestation who underwent amniocentesis was undertaken. Patients with multiple gestations were excluded. Intra-amniotic infection was defined as a positive culture for microorganisms, and intra-amniotic inflammation as an elevated amniotic fluid interleukin (IL)-6 concentration. IL-6 concentrations were determined by ELISA in 28 amniotic fluid samples available. Non-parametric statistics were used for analysis.

Results: 1) The prevalence of intra-amniotic infection was 5.7% (2/35), and that of IAI was 17.9% (5/28); 2) the gestational age at delivery was lower in patients with IAI than in those without IAI [29.4 weeks, interquartile range (IQR): 23.1-34.7 vs. 35.4 weeks, IQR: 33.9-36.9; P=0.028]; and 3) patients with placenta previa and IAI had a higher rate of delivery within 48 h (80% (4/5) vs. 19% (4/21); P=0.008) than those without IAI.

Conclusions: Patients with placenta previa presenting with vaginal bleeding have intra-amniotic infection in 5.7% of the cases, and IAI in 17.9%. IAI in patients with placenta previa and vaginal bleeding is a risk factor for preterm delivery within 48 h.