Assessment of rapid fetal fibronectin in predicting preterm delivery

Abstract

Objective: The aim of this study was to estimate the effectiveness of cervical fetal fibronectin assayed by the rapid fetal fibronectin assay in predicting preterm delivery in patients with signs or symptoms of preterm labor.

Methods: Patients with preterm labor between 24 and 34 weeks of gestation were included. At the time of speculum examination, fetal fibronectin samples were collected from the cervix. The probe was analyzed for fetal fibronectin using the rapid fetal fibronectin assay. Managing obstetricians were blinded to fetal fibronectin results. Outcome data were collected after delivery.

Results: One hundred seventy patients had fetal fibronectin samples and outcome data. The mean (+/- standard deviation) gestational age at delivery was 38.63 +/- 2.5 weeks among those with negative fetal fibronectin results (n = 124) and 35.71 +/- 3 weeks for those with positive results (n = 46; P < .001). The admission-to-delivery interval was 27.3 days shorter in the group with positive fetal fibronectin results (36.1 +/- 29.9 compared with 63.4 +/- 29.2; P < .001). The rapid fetal fibronectin assays were useful in predicting risk of delivery within 7, 14, or 21 days (sensitivity 81.8%, 87.5%, and 77.3%; specificity 76.7%, 79.2%, and 80.4; positive predictive value 19.6% [9/46], 30.4% [14/46], 37% [17/46]; negative predictive value 98.4% [122/124], 98.4% [122/124], and 96% [119/124], respectively).

Conclusion: In a population of patients with signs and symptoms of preterm labor, the presence of cervical fetal fibronectin is effective in predicting risk of delivery within 7, 14, or 21 days. The negative predictive values of fetal fibronectin using the Tli systems compared well with data from previous reports using enzyme-linked immunosorbent assay-based assays.

Level of evidence: III.