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Obstetrics
Evaluation of a quantitative fetal fibronectin test for spontaneous preterm birth in symptomatic women

Presented in part at the 15th annual conference of the British Maternal and Fetal Medicine Society, Glasgow, Scotland, UK, April 19-20, 2012.
https://doi.org/10.1016/j.ajog.2012.10.890Get rights and content

Objective

The purpose of this study was to determine whether quantification of cervicovaginal fluid fetal fibronectin (fFN) improves diagnostic accuracy of spontaneous preterm birth (sPTB) in symptomatic women.

Study Design

A prospective blinded predefined secondary analysis of a larger study of cervicovaginal fluid fFN concentration (nanograms per milliliter) in women symptomatic of preterm labor (n =300 women; 22-35 weeks' gestation) with a Hologic 10Q system (Hologic, Marlborough, MA). Clinicians were blinded to the result until after the delivery, but the qualitative Hologic TLIIQ fFN result was made available.

Results

The positive predictive value for sPTB (<34 weeks' gestation) increased from 19%, 32%, 61%, and 75% with increasing thresholds (10, 50, 200, and 500 ng/mL, respectively). Compared with <10 ng/mL fFN, the relative risk of delivery was 5.6 (95% confidence interval [CI], 1.05–29.57), 7.9 (95% CI, 1.38–45.0), 22.8 (95% CI, 3.84–135.5), and 51.3 (95% CI, 12.49–211.2; P < .01).

Conclusion

Quantitative fFN provides thresholds (10 and 200 ng/mL) in addition to the qualitative method (50 ng/mL) to discriminate the risk of sPTB in symptomatic women.

Section snippets

Materials and Methods

This was a prospective observational blinded study that involved a consecutive series of 300 symptomatic women with singleton pregnancies who underwent fFN sampling between 22+0 and 35+6 weeks' gestation for symptoms that are suggestive of threatened preterm labor. Such women had all presented themselves to an emergency assessment unit with symptoms of threatened preterm labor that the attending clinician believed warranted an fFN test. According to hospital protocol and the licensing

Results

Demographic and obstetrics characteristics for the study participants are described in Table 1. A total of 300 women with singleton pregnancies were eligible for analysis (21 women were removed according to the listed exclusion criteria; Figure 1). The mean gestational age of testing was 29+4 weeks' gestation (SD, 3.82 weeks), and 5.7% of the study population delivered spontaneously within 14 days of testing. There were no adverse events related to the test. Overall, there was a sPTB rate of

Comment

This is the first study, to our knowledge, to report the use of a novel bedside Rapid fFN 10Q system to quantify fFN concentrations within cervicovaginal fluid and to determine the subsequent risk of sPTB. The results clearly demonstrate that quantitative information has added value over the currently used qualitative fFN bedside test.

These data are supportive of previous reports from our group and others who reported improved prediction of preterm birth using values for the fFN concentration

Acknowledgments

We thank James T Kurtman (Loma Linda University, CA) and Manju Chandiramani (Imperial College, London) for their assistance in protocol development.

References (12)

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Supported by Tommy's Baby Charity number 1060508; Wellbeing of Women Research Scholarship Charity number 239281; and minority financial and equipment assistance from Hologic USA (Marlborough, MA). D.S.A. and A.H.S. received financial assistance from Hologic USA for providing educational talks on preterm birth.

The authors report no conflict of interest.

Reprints not available from the authors.

Cite this article as: Abbott DS, Radford SK, Seed PT, et al. Evaluation of a quantitative fetal fibronectin test for spontaneous preterm birth in symptomatic women. Am J Obstet Gynecol 2013;208:122.e1-6.

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