THE DIAGNOSTIC-ACCURACY OF CERVICOVAGINAL FETAL FIBRONECTIN IN PREDICTING PRETERM DELIVERY - AN OVERVIEW

Objective To determine the accuracy with which cervico-vaginal fetal f ibronectin predicts preterm delivery using systematic quantitative ove rview of the available literature. Design Online searching of MEDLINE database (1966 to April 1996), scanning of bibliography of known prima ry and review articles and review of recent journal issues, Study sele ction, assessment of study quality and data extraction were performed in duplicate under masked conditions. Likelihood ratios were generated in subgroups of symptomatic and asymptomatic pregnant women by poolin g data from different studies. An LR of >10 or <0.1 indicated conclusi ve changes in the pretest probability of preterm delivery while an LR of 5-10 or 0.2-0.1 indicated only moderate changes. Participants Seven hundred and twenty-three symptomatic women with threatened preterm la bour included in nine studies and 847 asymptomatic women (635 low risk and 212 high risk) included in six; studies selected for meta-analyse s. Main outcome measures Likelihood ratios for positive and negative t est results rising delivery at <37 and <34 weeks of gestation, and wit hin one week of testing as outcome measures. Results In symptomatic wo men a positive test predicted delivery <37 weeks of gestation with a p ooled likelihood ratio (LR) of 4.6 (95% CI 3.5-6.1) While a negative t est had a pealed LR of 0.5 (95% CI 0.4-0.6). For delivery <34 weeks of gestation, the pooled LR was 2.6 (95% CI 1.8-3.7) for a positive test and 0.2. (95% CI 0.1-0.5) for a negative test. For delivery within on e week of testing, the pooled LR was 5.0 (95% CI 3.8-6.4) for a positi ve test and 0.2 (95% CI 0.1-0.4) for a negative test. In asymptomatic women at low risk of delivery <37 weeks of gestation the pooled LR was 3.2 (95% CI 2.2-4.8) for a positive test and 0.8 (95% CI 0.7-0.9) for a negative test, In high risk asymptomatic women using delivery <37 w eeks of gestation as an outcome measure the pooled LR was 2.0 (95% CI 1.5-2.6) for a positive test and 0.4 (95% CI 0.2-0.8) for a negative t est. For delivery <34 weeks of gestation in high risk, asymptomatic wo men the pooled LR was 2.4 (95% CI 1.8-3.2) for a positive test and 0.6 (95% CI 0.4-0.9) for a negative test. Conclusion The presence of feta l fibronectin in cervico-vaginal mucus has limited accuracy in predict ing preterm delivery as the likelihood ratios for positive and negativ e test results generated only minimal to moderate changes in the prete st probability of preterm birth.