Cervicovaginal fetal fibronectin (FFN) for prediction of preterm delivery in symptomatic cases: a prospective study.

Objective: To assess the clinical value of cervicovaginal fetal fibronectin (FFN) in the prediction of preterm delivery (PTD) in women with signs and symptoms of preterm labor (PTL).

Method: This investigation prospectively studied a cohort of a women with symptoms of PTL, between 24 and 37 weeks' gestation with < 3 cm of cervical dilatation and intact membranes. Cases were evaluated in terms of maternal demographic characteristics like age, body mass index, number of parities, previous PTL history, Bishop scores at admission, gestational age at delivery, mode of delivery, use of tocolytic or steroids, presence of histologic chorioamnionitis, neonatal outcomes and delivery before 34 weeks' gestation as well as within seven days of admission.

Results: A total number of 68 cases were included in the study. There were no statistically significant differences between positive and negative FFN groups in terms of maternal characteristics, mode of delivery and adverse neonatal outcomes. However, FFN + cases had higher Bishop scores on admission (3.4 +/- 1.2 vs 2.5 +/- 0.3, p = 0.03) and lower gestational age at delivery (33.4 +/- 3.1 weeks vs 36.8 +/- 2.1 weeks, p = 0.002). Likelihood ratio (LR) for positive results was 1.83 (95% CI: 1.61-2.26) for predicting birth before 34 weeks' gestation, with a corresponding negative LR of 0.62 (95% CI: 0.3-1.2). LR for positive results was 4.34 (95% CI: 3.65-5.12) for predicting birth within seven days of testing, with a corresponding negative LR of 0.3 (95% CI: 0.2-0.5).

Conclusion: Based on the results of cervicovaginal FFN, positive tests represent an increased likelihood of PTD among women with symptoms of threatened preterm labor.