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). Cervical cerclage in situ gives more false positive fFN results¹ but its value in abdominal cerclage is unknown. The aim of this study is to assess the accuracy of quantitative fFN for prediction of PTB (<34 weeks’) in asymptomatic high-risk women with abdominal cerclage.

Method Secondary analysis of quantitative fFN results from EQUIPP study, taken between 20+0 and 24+6 week’ in asymptomatic women referred to specialist antenatal clinics (2010–2012), with a trans-abdominal, elective or ultrasound-indicated (emergency) cervical cerclage.

Results Quantitative fFN may be most accurate for predicting PTB at <34 weeks’ in women with abdominal cerclage (AUC 1.0 (95% CI 0.0–1.0), 0.82 (95% CI 0.70 – 0.94) and 0.60 (95% CI 0.45–0.75) respectively). For delivery at <34 weeks’ the sensitivity and specificity of fFN testing was lower in women with elective and emergency cervical cerclage compared to women with abdominal cerclage (Table 1). The positive predictive value of the test is similar between groups.

Conclusion Asymptomatic high-risk women with cervical cerclage in situ may have more false positive fFN test than women with an abdominal cerclage. Quantitative fFN is an accurate predictor of PTB in women with abdominal cerclage.

Reference

1. Duhig K, Chandiramani M, Seed PT, Briley AT, Kenyon AP & Shennan AH. Fetal fibronectin as a predictor of spontaneous preterm labour in asymptomatic women with cervical cerclage. BJOG 2009.116: 799–803