Objective: The purpose of the study was to assess the clinical value of fetal fibronectin assay in the group of women presenting with preterm contractions and cervical changes.
Study design: We prospectively evaluated 82 patients between 23-34 weeks of gestation presenting with signs and symptoms of preterm labor, intact membranes and cervical dilatation < 3 cm. In all cases cervico-vaginal samples were collected and assayed for the presence of fetal fibronectin. The primary outcome was delivery < or = 28 days from examination.
Results: The rate of preterm delivery (< 37 weeks) was 25.6% (21/82) and 17.1% (14/82) of the patients delivered < or = 28 days from the examination. The mean Bishop score was significantly higher in patients delivered < 28 days (5.9 +/- 1.2 vs 4.7 +/- 1.4; p = 0.004). Positive result of fFN (> 0.05 mg/ml) was found in 71.4% of patients that were delivered < or = 28 days and in 7.4% delivered > 28 days (p < 0.001). For predicting delivery < or = 28 days the positive fFN testing had sensitivity of 71.4%, specificity of 92.7%, PPV of 66.7% and NPV of 94%. The cutoff value for Bishop's score > or = 5 had sensitivity of 85.7% and specificity of 48.5%. Performing fFN testing only in patients with Bishop score > or = 5 resulted in the sensitivity of 71.4%, specificity of 95.6%, PPV of 76.9% and NPV of 94.2%.
Conclusions: Fetal fibronectin is a very good predictor of imminent preterm delivery. It needs further research whether performing of the fFN assay can be limited only to the patients with the estimated Bishop's score > or = 5.