Accuracy of cervicovaginal fetal fibronectin test in predicting risk of spontaneous preterm birth: systematic review

Abstract

Objective To determine the accuracy with which a cervicovaginal fetal fibronectin test predicts spontaneous preterm birth in women with or without symptoms of preterm labour. Design Systematic quantitative review of studies of test accuracy. Data sources Medline, Embase, PASCAL, Biosis, Cochrane Library, Medion, National Research Register, SCISEARCH, conference papers, manual searching of bibliographies of known primary and review articles, and contact with experts and manufacturer. Study selection Two reviewers independently selected and extracted data on study characteristics, quality, and accuracy. Data extraction Accuracy data were used to form 2×2 contingency tables with spontaneous preterm birth before 34 and 37 weeks' gestation and birth within 7-10 days of testing (for symptomatic pregnant women) as reference standards. Data were pooled to produce summary receiver operating characteristic curves and summary likelihood ratios for positive and negative test results. Data synthesis 64 primary articles were identified, consisting of 28 studies in asymptomatic women and 40 in symptomatic women, with a total of 26 876 women. Among asymptomatic women the best summary likelihood ratio for positive results was 4.01 (95% confidence interval 2.93 to 5.49) for predicting birth before 34 weeks' gestation, with corresponding summary likelihood ratio for negative results of 0.78 (0.72 to 0.84). Among symptomatic women the best summary likelihood ratio for positive results was 5.42 (4.36 to 6.74) for predicting birth within 7-10 days of testing, with corresponding ratio for negative results of 0.25 (0.20 to 0.31). Conclusion Cervicovaginal fetal fibronectin test is most accurate in predicting spontaneous preterm birth within 7-10 days of testing among women with symptoms of threatened preterm birth before advanced cervical dilatation.

Ultrasound assessment of cervical length in threatened preterm labor

“…The alternative to sonographic measurement of cervical length in predicting the outcome of women presenting in threatened preterm labor is biochemical assessment for the presence of fetal fibronectin in cervicovaginal secretions 11 . A recent systematic review of 40 studies on fetal fibronectin in women presenting with threatened preterm labor reported that the likelihood ratio for positive results for predicting delivery within 7-10 days of presentation was 5.42 (95% CI 4.36-6.74) and the ratio for negative results was 0.25 (95% CI 0.20-0.31) 12 . In a multicenter study involving 763 women presenting with threatened preterm labor, fetal fibronectin was positive in 20% of women.…”

New biomarkers for the prediction of spontaneous preterm labour in symptomatic pregnant women: a comparison with fetal fibronectin

“…Based on these results, fFN yielded a sensitivity of 66.7%, specificity of 87.9%, PPV of 36.4% and NPV of 96.2% (Table 3), comparable with other published data. 5,13,14 Women presenting with symptoms of PTL with cervical change (>3 cm dilation, Group 3) were not tested with the QuikCheck TM fFN kit. Utilising the same 64 women in whom albumin and VDBP were both assayed, a comparison of the efficacy of fFN with a combined biomarker model (albumin and VDBP) for the prediction of labour within 7 days was made.…”

“…These tests, however, have limited application in identifying women who will deliver preterm, because of their relatively low sensitivity and poor positive predictive values (PPVs). 5,6 In contrast, their utility relies on their high negative predictive value (NPV) in recognising women who are unlikely to deliver preterm.…”

Screening to prevent spontaneous preterm birth: systematic reviews of accuracy and effectiveness literature with economic modelling

“…For these women, there is a need to identify those who will go on to deliver prematurely because the key clinical decisions following testing relate to immediate management and outcome. For example, if cervicovaginal fetal fibronectin testing could predict spontaneous preterm birth among these women before advanced cervical dilatation, 23 then antenatal maternal intramuscular corticosteroid injection may be administered to accelerate fetal lung maturity to prevent respiratory distress syndrome. 24 In utero transfer to a tertiary intensive neonatal care unit able to care for the premature neonate may also be considered.…”