Use of fetal fibronectin in clinical practice.

Preterm delivery remains a worldwide problem hindered by many unknowns, not the least of which is an inability to detect patients at risk for this complication of pregnancy. A unique form of fibronectin identified in the extracellular matrix surrounding the extravillous trophoblast at the uteroplacental junction contains an epitope called the "oncofetal domain," which is recognized by the monoclonal antibody FDC-6. When detected in cervicovaginal secretions of both symptomatic patients as well as asymptomatic women who have risk factors for early deliver, fetal fibronectin seems to be a marker for preterm delivery with a good positive predictive value (40-60 percent). A negative result has a negative predictive value of 99.5 percent for birth within 7 days and 92 percent for delivery before 37 weeks in those patients with signs and symptoms of preterm labor. In low-risk asymptomatic patients, the positive predictive value is lower (15-25 percent), but is important because women in this group, destined to deliver as a consequence of preterm labor, may have no other signs or symptoms to forebode preterm delivery. Fetal fibronectin testing could also be important in women in spurious preterm labor who may eventually deliver before 37 weeks' gestation. Although specific interventional studies are still needed, this test is an important step forward in the provider's armamentarium to reduce the impact of a preterm delivery.