Prediction of preterm delivery by fetal fibronectin in symptomatic and asymptomatic women with cervical length ≤20 mm.

OBJECTIVE: To evaluate the diagnostic accuracy of cervicovaginal fetal fibronectin (fFN) in predicting preterm delivery (PTD) in symptomatic and asymptomatic women with cervical length (CL) ≤ 20 mm.

METHODS: A retrospective cohort study on pregnant singleton women admitted for CL ≤ 20 mm, with or without uterine contractions, between 22 and 34 weeks. For each group, symptomatic and asymptomatic, the following outcomes were evaluated: PTD before 37 and 34 weeks, delivery within 48 h, 7, 14 and 21 days after fibronectin sampling.

RESULTS: 128 women admitted for CL ≤ 20 mm were identified. Of these, 43 had uterine contractions, while 85 were asymptomatic. A positive fFN test was detected in 33% of symptomatic patients and it was significantly associated with PTD < 37 and 34 weeks and within 48 hours, 7, 14 and 21 days from admission (p < 0.05). After logistic regression analysis, fFN remained an independent predictor for all outcomes. In the asymptomatic group fFN test was positive only in 6% of patients, and a positive result was not significantly associated with any of the outcomes.

CONCLUSIONS: In women with contractions and CL ≤ 20 mm, fFN is an effective marker of PTD. Sensitivity and specificity rates for PTD within 7-14 days are higher than those reported in studies including women with CL > 20 mm. In asymptomatic women, fFN appeared not as effective in predicting PTD.