Negative fFN, Who is Still Managed Aggressively and Does it Help?

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Abstract

Objective: Elevated levels of fetal fibronectin (fFN) in cervicovaginal secretions beyond 22 weeks gestation are used as a predictor of preterm birth in patients suspected of being in preterm labor. Previous studies have documented a negative predictive value of 97-99.5% of delivering within 7 days of testing. Providers sometimes disregard a negative result and manage the patient aggresively. Our objective was to identify which patients with a negative fFN were being managed aggressively, and if outcomes were improved with such management.

Study Design: Charts were reviewed from 121 patients evaluated in our obstetrical triage unit for "rule-out preterm labor" with negative fFN results over a 2 year period. Patients with singleton pregnancies seen between 22 and 33 6/7 weeks were included. Patient characteristics, management, and outcomes were recorded.

Results: 80 patients were managed expectantly, 41 were managed aggressively (18 were admitted, 29 were given tocolytics, 15 received steroids, 8 received antibiotics). The group managed aggressively were more likely to be dilated 1cm or more (27% vs. 3%, p<.001), or contracting at least every 8 minutes (68% vs. 23%, p<.001). Parity, prior preterm births, age and gestational age at testing were similar between the groups. None of the patients delivered within 7 or 14 days of fFN testing. The rates of preterm birth <37 weeks, <35 weeks and <32 weeks, and fFN to delivery interval were similar between the 2 groups. There was no advantage seen to aggressive management even when analyzing only the "high risk" patients (dilated 2cm, effaced >80%, contracting at least every 4 minutes, or prior preterm birth).

Conclusion: Patients with risk factors for preterm birth are more likely to be aggressively managed in the face of a negative FFN. This aggressive management does not improve outcomes.

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0002-9378/$ - see front matter
doi:10.1016/j.ajog.2006.10.853
American Journal of Obstetrics and Gynecology
Volume 195, Issue 6, Supplement S (December 2006)