The diagnostic value of fetal fibronectin testing in clinical practice

Aim: To evaluate the clinical management to withhold treatment for preterm labor in symptomatic women with an intermediate cervical length and negative fetal fibronectin (fFN) testing. Methods: A retrospective cohort study was performed in a tertiary care teaching hospital in the Netherlands. Pregnant women with a gestational age between 23+5 to 34+0 weeks, with the presence of regular uterine contractions accompanied by a cervical length between 15 and 30 mm and intact membranes, who underwent fFN testing were included to obtain the diagnostic value of fFN testing for preterm delivery within 7 days. Results: Fetal fibronectin testing has an extremely high negative predictive value (100%) and sensitivity (100%) for delivery within 7 days, in singleton and multiple pregnancies. However, specificity (64%) and positive predictive value (10%) of fFN testing in singleton pregnancies are low. Blood present on the fFN sample does not affect the reliability of the fFN test; the negative predictive value remains 100%. Conclusion: Women with symptoms of early preterm labor, intact membranes, a cervical length between 15 and 30 mm and negative fFN testing do not deliver within 7 days. Administration of corticosteroids and tocolytics can safely be withhold. Furthermore, blood on the fFN sample does not change the reliability of the fFN test.