Selective use of fetal fibronectin detection after cervical length measurement to predict spontaneous preterm delivery in women with preterm labor.
OBJECTIVE
The purpose of this study was to determine whether selective use of fetal fibronectin detection after ultrasound measurement of cervical length predicts preterm delivery in symptomatic patients better than either indicator alone.


METHODS
This prospective blinded study performed both tests on 359 women hospitalized for preterm labor between 18 and 34 completed weeks' gestation. The primary outcome was preterm delivery before 35 weeks'gestation.


RESULTS
Among the 359 women included, 48 (13.4%) delivered before 35 weeks' gestation. The sensitivity, specificity, and positive and negative predictive values of cervical length < or = 25 mm were 75%, 63%, 24%, and 94%, respectively, and of fetal fibronectin > or = 50 ng/mL, 63%, 81%, 33%, and 93%. Fetal fibronectin detection was significantly (P < .001) more specific than cervical length measurement. For selective use of fetal fibronectin detection after cervical length measurement, the test was considered positive if cervical length was < or = 15 mm or if cervical length was between 16 and 30 mm with fetal fibronectin > or = 50 ng/mL. The predictive values of this test were not significantly different from those of fetal fibronectin detection (67%, 81%, 36%, and 94%). This strategy could have avoided 200 fibronectin tests.


CONCLUSIONS
Selective use of fetal fibronectin detection after cervical length measurement is more specific than cervical length and as effective as fetal fibronectin assays in the entire population of women in preterm labor for predicting preterm birth.
Schmitz
Thomas
T
Maternité Port-Royal, Paris, France. thomas.schmitz@cch.aphp.fr
Maillard
Françoise
F
Bessard-Bacquaert
Sandrine
S
Kayem
Gilles
G
Fulla
Yvonne
Y
Cabrol
Dominique
D
Goffinet
François
F
D000328:Adult; D002584:Cervix Uteri / Q000000981:diagnostic imaging*; D005260:Female; D005333:Fetus / Q000378:metabolism*; D005353:Fibronectins / Q000378:metabolism*; D006801:Humans; D007752:Obstetric Labor, Premature / Q000000981:diagnostic imaging* / Q000378:metabolism*; D011237:Predictive Value of Tests; D011247:Pregnancy; D047928:Premature Birth; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D016037:Single-Blind Method; D014463:Ultrasonography
D005353:Fibronectins