Quantitative Fetal Fibronectin to Predict Preterm Birth in Asymptomatic Women at High Risk. Issue 5 (May 2015)

• Record Type: Journal Article
• Authors: Abbott, Danielle S.; Hezelgrave, Natasha L.; Seed, Paul T.; Norman, Jane E.; David, Anna L.; Bennett, Phillip R.; Girling, Joanna C.; Chandirimani, Manju; Stock, Sarah J.; Carter, Jenny; Cate, Ruth; Kurtzman, James; Tribe, Rachel M.; Shennan, Andrew H.
• Is Part Of: Obstetrics and gynecology. Volume 125:Issue 5(2015)
• Publication Date: 2015-05
• Subjects: Obstetrics -- Periodicals; Gynecology -- Periodicals; 618
• DOI: 10.1097/AOG.0000000000000754
• Languages: English
• ISSNs: 0029-7844

Abstract

Abstract : OBJECTIVE: To evaluate the diagnostic accuracy of cervicovaginal fluid quantitative fetal fibronectin, measured by a bedside analyzer, to predict spontaneous preterm birth before 34 weeks of gestation. METHODS: We conducted a prospective masked observational cohort study of cervicovaginal fluid quantitative fetal fibronectin concentration in asymptomatic women at high risk of spontaneous preterm birth (n=1, 448; 22–27 6/7 weeks of gestation) measured using a rapid bedside analyzer. The routine qualitative result (positive–negative) was made available to clinicians at the time of testing, but the quantitative result remained blinded until after delivery. RESULTS: Spontaneous preterm birth (less than 34 weeks of gestation) increased from 2.7%, 11.0%, 14.9%, 33.9%, and 47.6% with increasing concentration of fetal fibronectin (less than 10, 10–49, 50–199, 200–499, and 500 ng/mL or greater, respectively). A threshold of 200 ng/mL had a positive predictive value of 37.7 (95% confidence interval [CI] 26.9–49.4) with specificity 96% (95% CI 95.3–97.3). Women with a fetal fibronectin concentration of less than 10 ng/mL had a very low risk of spontaneous preterm birth at less than 34 weeks of gestation (2.7%), no higher than the background spontaneous preterm birth rate of the general hospital population (3.3%). The quantitative fetal fibronectin test predicted birth at less than 34 weeks of gestation with an area under the curve (AUC) of 0.78 (95% CI 0.73–0.84) compared with the qualitative test AUC 0.68 (95% CI 0.63–0.73). Quantitative fetal fibronectin discriminated risk of spontaneous preterm birth at less than 34 weeks of gestation among women with a short cervix (less than 25 mm); 9.5% delivered prematurely less than 10 ng/mL compared with 55.1% greater than 200 ng/mL ( P <.001). DISCUSSION: Alternative risk thresholds (less than 10 ng/mL and greater than 200 ng/mL) improve accuracy when using quantitative fetal fibronectin measurements to define risk of spontaneous preterm birth. This is particularly relevant for asymptomatic women with a short cervix. LEVEL OF EVIDENCE: II Abstract : Point-of-care quantification of cervicovaginal fetal fibronectin accurately predicts spontaneous preterm birth before 34 weeks of gestation in asymptomatic women at high risk.