Which finding would improve diagnostic accuracy of imminent delivery for a woman in preterm labor?

• A. Presence of fetal fibronectin in cervicovaginal fluid
• B. Cervical length of 30 mm measured by transabdominal ultrasound
• C. Effacement of less than 80%
• D. Maternal fever

Answer: (A)

Fetal fibronectin in cervicovaginal secretions acts as a biomarker for the integrity of the placental–decidual interface. In women with preterm labor, its presence between roughly 22 and 34 weeks indicates disruption of that barrier and increases the probability of delivery within the next 7 days. This test is especially useful because it has a high negative predictive value: if the test is negative, the chance of imminent delivery is very low, which helps avoid unnecessary hospitalization and interventions. A positive result raises the clinician’s suspicion for imminent delivery and helps guide closer monitoring and timely decisions about management, particularly when used alongside cervical length assessment.

A cervical length of 30 mm, especially when measured transabdominally, suggests a relatively long cervix and a lower short-term risk of delivery; transvaginal measurement would be more accurate, but overall a longer cervix does not indicate imminent delivery. Effacement less than 80% suggests the cervix is not yet ready, which also argues against imminent delivery. Maternal fever points to possible infection, such as chorioamnionitis, and would change management, but fever alone doesn’t provide as reliable a short-term prediction of delivery timing as a fetal fibronectin result.