The frequency and clinical significance of intra-amniotic inflammation in patients with a positive cervical fetal fibronectin

OBJECTIVE: A positive fetal fibronectin result In cervicovaginal fluid is a powerful predictor of preterm delivery and is considered a marker for uppe r genital tract infection (ie, intrauterine Infection). Treatment with anti microbial agents is being considered in patients with a positive fetal fibr onectin test of cervico/vaginal fluid. This study was undertaken to determi ne the frequency and clinical significance of intra-amniotic infection/infl ammation in patients with a positive fetal fibronectin. STUDY DESIGN: A total of 1709 pregnant women (gestational age, 23-31 weeks) were screened for cervical fetal fibronectin. Patients with a positive fib ronectin were offered amniocentesis for the diagnosis of intra-amniotic inf ection and treatment with antibiotics. Amniocentesis was performed in 58 pa tients with a positive fibronectin test (> 50 ng/mL). Amniotic fluid was cu ltured for aerobic/anaerobic bacteria and mycoplasmas. Polymerase chain rea ction assay for Ureaplasma urealyticum was performed. Interleukin-6 concent rations were measured by a specific immunoassay. Nonparametric statistics w ere used for analysis. RESULTS: None of the patients with a positive fibronectin had a positive am niotic fluid culture. U urealyticum was detected in 1 case (1.8%) with the polymerase chain reaction assay, Amniotic fluid IL-6 was elevated (>2.5 ng/ mL) in 5.3% of patients (3/57 patients); all of these patients delivered pr eterm neonates. There was no relationship between amniotic fluid IL-6 and c ervical fibronectin concentration (r = 0.14; P > .1). Patients who delivere d preterm (< 34 weeks) had higher median amniotic fluid IL-6 and cervical f etal fibronectin concentrations than those patients who delivered after 34 weeks (IL-6: median, 2.1 ng/mL [range, 0.1-25.3 ng/mL] vs median, 0.3 ng/mL [0.03-2.4 ng/mL]; P < .05; fibronectin: median, 509 ng/mL [260-> 1000 ng/m L] vs median, 155 ng/mL [50-889 ng/mL]; P < .01). CONCLUSION: Intra-amniotic infection was detected in 1.8% of cases with a p ositive fibronectin In the cervical fluid; intra-amniotic inflammation was present in 5.3% of cases. All patients with a positive fetal fibronectin an d intra-amniotic inflammation delivered preterm neonates.