Is It Time To Stop Using Fetal Fibronectin In Diagnosis of Preterm Labor?

Fetal fibronectin (fFN) has long been used as a biomarker to predict preterm labor. fFN sits at the interface between the amniotic sac and the uterine lining, thus its presence in vaginal secretions toward the end of gestation may indicate the onset of labor. Preterm labor, defined as labor that occurs before 37 weeks of gestation, is the leading cause of neonatal morbidity and mortality in the United States.

In the scientific session on Thursday, December 17 at 11:00 am Central, “Laboratorian and Clinician Perspective on Proper Utilization of Preterm Labor Tests,” speakers focus on the need for a better biomarker to predict preterm labor and which candidate markers are under investigation.

Speaker Yusheng Zhu, PhD, shares his experience that lead to discontinuation of fFN at Penn State University Hershey Medical Center. Annual test volume of fFN decreased from 74 in 2008 to 2 thus far in 2020, he says. Zhu attributes the steady decrease to a rigorous specimen collection process, cost of the test, and most importantly, a lack of association between positive fFN tests and improved perinatal outcomes.

The negative predictive value (NPV) of fFN is higher in cases where preterm labor prevalence is low, leading to its proposed use as a rule-out test in women with suggestive signs and symptoms. Zhu also notes that in the majority of U.S. medical centers, the prevalence of preterm birth is low, which means the high NPV does little to change the pre-test probability of disease.

In areas where preterm birth prevalence is high, the positive predictive value increases, Zhu notes. In terms of clinical utility, “the best use policy probably still depends on local contingencies, future cost-effectiveness analysis, and comparison with other more recent available biochemical markers,” Zhu says.

Zhu also delves into other prominent biomarkers such as placental alpha macroglobulin-1 (PAMG-1), insulin-like growth factor-binding protein-1 (IGFBP-1), and alpha-fetoprotein (AFP) in predicting premature birth and shows a comparison between these biomarkers and fFN.

In addition, Zhu highlights some of the new approaches in the fields of proteomics, metabolomics, and lipidomics. Diagnostic tools to determine preterm labor are critical, as none of the available options are ideal, Zhu says. He hopes the omics-based multiplex assays can provide much-needed options.

Another speaker, Serdar Ural, MD, provides a clinician’s perspective on fFN, showing how a patient with clinically diagnosed preterm labor is managed at his institution. He explains how, among other procedures, patients are limited to bedrest, magnesium sulfate is given to postpone preterm labor, and betamethasone is given for fetal lung maturity.

Attendees of this session will come away understanding more about the importance of why a better diagnostic tool is needed for preterm labor diagnosis and appreciate the collaboration between clinicians and laboratorians in the search for answers.