Fibronectin testing combined with cervical length assessment estimating the risk of birth before 35 weeks in high risk patients – A retrospective study

Introduction: Preterm birth (PB) is the leading cause of neonatal mortality and morbidity in the industrialized world. However, the identification of women at risk for PB remains a challenge. Sonographic assessment of cervical length (CL) has been the gold standard in estimating the risk of PB. Currently, fetal fibronectin (fFN) has become an additional instrument. Objective: To determine whether two-step testing (CL plus fFN) increases overall specificity, sensitivity, positive and negative predictive values and whether women with a high risk for PB assessed by CL measurement, but with a negative fFN are actually to be classified as at lower risk for PB. Furthermore, we wanted to estimate whether an ambulatory management of patients with PTL would be feasible and cost effective. Methods: 65 patients with preterm labor were evaluated. Inclusion criteria were contractions >4/20 min, gestational age between 22 and 35 weeks of gestation, no pPROM, no bleeding and no vaginal infections. Singleton and twin pregnancies were evaluated separately. The primary outcome was delivery within the next 14 days. Secondary outcome was the potential amount of money saved with an ambulatory management. Results: Negative predictive values (NPV) for delivery within 14 days for fFN and CL (0.97 and 0.93) were similar, but for the period of birth within 50 days, the NPV of fFN was higher than for CL (0.75 versus 0.6). The average costs for hospitalizing a patient were 700 CHF per day, not including costs for medication and medical attention. Conclusion: Two-step testing in patients symptomatic for PTL is reliable in estimating the patient's risk for preterm birth. Furthermore it may be a tool for a more cost effective management of patients with PTL.

Cervical length - Fibronectin - pretem birth - preterm labour