The Utility Of Fetal Fibronectin In Asymptomatic Singleton And Twin Pregnancies With A Cervical Length <= 10 Mm

Objective:To examine the utility of fetal fibronectin (fFN) for predicting spontaneous preterm birth (PTB) in asymptomatic women with a cervical length (CL) <= 10 mm compared to those with a CL 11-25 mm. Methods:Data was collected on all women with nonanomalous singleton and twin gestations who underwent transvaginal CL at a single institution between 2009 and 2012. Women with an incidental short cervix (CL <= 25 mm) between 22 and 32 weeks who had an fFN result within 7 days thereafter were included. Indicated preterm deliveries at <14 days of fFN, women who underwent cerclage placement, and terminations of pregnancy were excluded. The primary outcome was spontaneous PTB within 7 and 14 days of the fFN. Sensitivity, specificity, and positive (PPV) and negative predictive value (NPV) of fFN for a CL <= 10 mm was calculated for singletons and twins and compared to those with a CL 11-25 mm. Results:Of the 213 women included, 117 (54.9%) were singletons and 96 (45%) were twins. Baseline characteristics were similar between those with a CL <= 10 mm and with a CL 11-25 mm in both singletons and twins. The NPV of fFN for delivery within 7 days in singletons and twins with a CL <= 10 mm was 100%, similar to those with a CL 11-25 mm (93-100%). The NPV of fFN for delivery within 14 days in singletons and twins with a CL <= 10 mm remained high (87.5-100%) when compared to those with a CL 11-25 mm (93-100%). The PPV of fFN for delivery within 7 and 14 days in both singletons and twins with a CL <= 10 mm was low (10-25%) and similar to those with a CL 11-25 mm (7.1-24.4%). Conclusions:The NPV of fFN in asymptomatic singleton and twin pregnancies with a CL <= 10 mm is high and comparable to the NPV of fFN in women with a longer CL. Routine fFN collection in this select population should be considered as it may avoid unnecessary and costly admissions, as well as assist with timing of antenatal corticosteroids.