Isolation of Ureaplasma urealyticum From the Amniotic Cavity and Adverse Outcome in Preterm Labor

OBJECTIVE: To determine the relationship between the presence of Ureaplasma urealyticum in the amniotic cavity and adverse maternal and perinatal outcome in women with preterm labor. METHODS: Amniocentesis was performed in 181 patients with preterm labor and intact membranes. Amniotic fluid (AF) was cultured for aerobic and anaerobic bacteria and mycoplasmas. Patients were divided into three groups according to the results of AF culture: those with negative AF cultures (n=160), those with positive AF cultures and in whom the only microbial isolate was U urealyticum (n=11), and those with positive cultures for non-ureaplasmas or mixed microorganisms (n=10). Survival techniques were used for analysis. RESULTS: The prevalence of positive AF cultures in which the only microbial isolate was Uurealyticum was 6.1% (11 of 181), and of positive cultures with non-ureaplasmas or mixed microorganisms was 5.5% (10 of 181). The amniocentesis-to-delivery interval was significantly shorter in patients with positive cultures limited to U urealyticum than in those with negative cultures (median 7 range 0.1-149 hours versus median 264 0.1-2659 hours, P < .001). Preterm delivery within 48 hours, 72 hours, and 7 days was more frequent in patients with U urealyticum in the AF than in those with sterile AF (48 hour: 91% versus 33%; 72 hour: 91% versus 36%; 7 days: 100% versus 45%, P < .001 for each). Patients with positive AF cultures limited to U urealyticum had a significantly higher rate of adverse perinatal outcome than those with negative culture. Adverse outcomes included low gestational age at birth, low birth weight, histologic chorioamnionitis, significant neonatal morbidity, and perinatal death. CONCLUSION: Microbial invasion of the amniotic cavity with U urealyticum is a risk factor for impending preterm delivery and adverse perinatal outcome.