Which factors contribute to false-positive, false-negative, and invalid results in fetal fibronectin testing in women with symptoms of preterm labor?

Merel M.C. Bruijn, Frederik J.R. Hermans, Jolande Y. Vis, Femke F. Wilms, Martijn A. Oudijk, Anneke Kwee, Martina M. Porath, Guid Oei, Hubertina C.J. Scheepers, Marc E.A. Spaanderman, Kitty W.M. Bloemenkamp, Monique C. Haak, Antoinette C. Bolte, Frank P.H.A. Vandenbussche, Mallory D. Woiski, Caroline J. Bax, Jérôme M.J. Cornette, Johannes J. Duvekot, Bas W.A.N.I.J. Bijvank, Jim Van EyckMaureen T.M. Franssen, Krystyna M. Sollie, Joris A.M. Van Der Post, Patrick M.M. Bossuyt, Marjolein Kok, Ben W.J. Mol, Gert Jan Van Baaren

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4 Citations (Scopus)


Objective We assessed the influence of external factors on false-positive, false-negative, and invalid fibronectin results in the prediction of spontaneous delivery within 7 days. Methods We studied symptomatic women between 24 and 34 weeks' gestational age. We performed uni- and multivariable logistic regression to estimate the effect of external factors (vaginal soap, digital examination, transvaginal sonography, sexual intercourse, vaginal bleeding) on the risk of false-positive, false-negative, and invalid results, using spontaneous delivery within 7 days as the outcome. Results Out of 708 women, 237 (33%) had a false-positive result; none of the factors showed a significant association. Vaginal bleeding increased the proportion of positive fetal fibronectin (fFN) results, but was significantly associated with a lower risk of false-positive test results (odds ratio [OR], 0.22; 95% confidence intervals [CI], 0.12-0.39). Ten women (1%) had a false-negative result. None of the investigated factors was significantly associated with a significantly higher risk of false-negative results. Twenty-one tests (3%) were invalid; only vaginal bleeding showed a significant association (OR, 4.5; 95% CI, 1.7-12). Conclusion The effect of external factors on the performance of qualitative fFN testing is limited, with vaginal bleeding as the only factor that reduces its validity.

Original languageEnglish
Pages (from-to)234-239
Number of pages6
JournalAmerican Journal of Perinatology
Issue number3
Publication statusPublished - 1 Feb 2017


  • external factors
  • fetal fibronectin
  • prediction
  • preterm delivery
  • Uterine Hemorrhage/metabolism
  • Endosonography
  • Humans
  • Risk Factors
  • False Negative Reactions
  • Obstetric Labor, Premature/diagnosis
  • False Positive Reactions
  • Fibronectins/analysis
  • Gestational Age
  • Soaps
  • Vagina/chemistry
  • Pregnancy
  • Young Adult
  • Coitus
  • Adult
  • Female


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