Fetal fibronectin detection as a predictor of preterm birth in actual clinical practice

OBJECTIVE: This study was undertaken to determine whether fetal fibronectin determination is more useful for predicting preterm delivery in clinical p ractice than it has appeared to be in prospective blinded studies. STUDY DESIGN: Charts of 151 patients with fetal fibronectin tests performed during 2 years were reviewed. Patients were included if they had symptoms of preterm labor, a singleton pregnancy at 24 to 35 weeks' gestation, intac t membranes, and cervical dilatation less than or equal to 3 cm. RESULTS: Complete data were available for 85 tests. For delivery within 7 d ays after specimen collection the sensitivity, specificity, positive predic tive value, and negative predictive Value were 89%, 84%, 40%, and 98%, resp ectively. The positive predictive value was greater (P < .002) than those r eported in three prospective studies evaluating delivery within 7 days in p atients with symptoms. Gestational age at delivery and birth weight were lo wer for patients with positive results (P < .0001 and P < .006, respectivel y). Patients with positive results were also treated more with tocolysis, c orticosteroid use, and hospitalization than were patients with negative res ults. For direct comparison with studies of patients with cervical dilatati on <3 cm, only 4 patients with cervical dilatation of 3 cm were enrolled. A ll 4 had negative results of fetal fibronectin testing, and their outcomes therefore did not affect the positive predictive value. CONCLUSION: The positive predictive value of fetal fibronectin measured in actual clinical practice was significantly greater for delivery within 7 da ys than has been reported in blinded prospective studies.