Clinical Application of Quantitative Foetal Fibronectin for the Prediction of Preterm Birth in Symptomatic Women

Aim: To evaluate the clinical application of the new Hologic quantitative foetal fibronectin (qfFN) bedside test for the prediction of spontaneous preterm birth (sPTB) in patients with symptoms suggestive of spontaneous threatened preterm labour (sPTL). Methods: A prospective observational study with 154 pregnant women presenting signs and symptoms of sPTL was conducted. These women were subjected to a qfFN test between 22 and 35 weeks of gestation For each cut-off threshold, the ability to predict sPTB at within 14 days of conducting the test and <37 weeks was assessed by calculating the positive predictive value (PPV), negative predictive value (NPV), likelihood ratios, odds ratios, sensitivity, and specificity. Results: For the outcome of delivery within 14 days of the test, qfFN <10 ng/mL had a 100% NPV and >200 ng/mL produced a 50.0% PPV; thus, qfFN added enhanced discrimination between high- and low-risk patients. The overall rate of sPTB (<37) was 13.3% (16/120), which increased progressively with increasing levels of fFN, with rates of 9.8% (8/81), 11.5% (3/26), 14.2% (1/7), 50% (3/6) within the 4 categories (fFN 0-9, 10-49, 50-200, 200+) respectively. Conclusions: The use of the qfFN testing in symptomatic patients allowed for more accurate identification of women at risk of sPTB and thus more directed management.