Low Incidence of Positive Amnionic Fluid Cultures in Preterm Labor at 27-32 Weeks in the Absence of Clinical Evidence of Chorioamnionitis

In order to determine the utility of amniocentesis for detecting subclinical chorioamnionitis in asymptomatic afebrile women in preterm labor with intact membranes, we enrolled 47 women between 27-32 weeksʼ gestation in a prospective study. After enrollment, 38 women fulfilled all clinical and laboratory criteria for the study; nine women were excluded because they had a leukocyte count exceeding 15,000/µL. None of the 38 asymptomatic afebrile women had a positive culture from the amnionic fluid for bacteria, fungi, Mycoplasma hominis, Ureaplasma urealyticum, Chlamydia trachomatis, or any viruses. Sepsis was not proved in any of the 38 infants delivered to these patients. There was a clear relationship between histologic evidence of chorioamnionitis and failure of tocolytic therapy. Fetal lung profiles were mature in 29% of the amnionic fluid samples from 30-32 weeksʼ gestation, but in none of the amnionic fluid samples before 30 weeks. Amniocentesis does not seem useful to detect chorioamnionitis in asymptomatic afebrile women with preterm labor and intact membranes at 27-32 weeksʼ gestation, and should be reserved for those cases in which information about fetal lung maturity would be helpful.