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Abstract
Background Preterm birth (PTB) remains a significant cause of neonatal morbidity and mortality. The most accurate predictors of PTB are ultrasound determined cervical length (CL) and fetal fibronectin (fFN)1. Quantitative fFN can be used to further outline risk in symptomatic women2. New devices are appearing on the market.
Objectives To compare the capacity of two different quantitative fetal fibronectin (fFN) systems to predict cervical shortening in asymptomatic women at high-risk of PTB.
Methods Women underwent CL measurement and fFN testing between 20+0 and 24+6 week of gestation in the Preterm Surveillance Clinic at St. Thomas’ Hospital (August to November 2012). Fetal fibronectin samples were run using a bedside immunoassay system (10Q system, Hologic, Marlborough) and bedside chemiluminescence system (DryLab, Audit Diagnostics, Ireland).
Results 130 fFN tests were taken from 89 women. Comparison of all test results showed considerable difference between methods (R2 0.22). A short cervix (<25 mm) was found in 14 women. The 10Q system was able to significantly detect cervical shortening (Area under the curve 0.69, 95% CI 0.57–0.82, p = 0.002), however DryLab system could not (AUC 0.52, 95% CI 0.35–0.71, p = 0.12). Hologic 10Q had a better positive predictive value than DryLab (29% vs. 22% respectively), but similar negative predictive values (88% vs 87% respectively). Secondary outcomes such as gestational age at delivery will be presented.
Conclusion Quantitative fFN is associated with cervical shortening and therefore risk of imminent preterm birth in asymptomatic women. Not all commercial devices are accurate.
References
Bolt LA, Chandiramani M, De Greef A, Seed PT, Kurtzman J & Shennan AH. The Value of combined cervical length measurement and fetal fibronectin testing to predict spontaneous preterm birth in asymptomatic high-risk women. J Matern Fetal Neonatal Med 2011;24(7):928–932.
Abbott DS, Radford SK, Seed OT, et al. Evaluation of quantitative fetal fibronectin test for spontaneous preterm birth in symptomatic women. AJOG 2012.