title: The predictive value of quantitative fibronectin testing in combination with cervical length measurement in symptomatic women.
abstract: BACKGROUND
  The combination of the qualitative fetal fibronectin test and cervical length measurement has a high negative predictive value for preterm birth within 7 days; however, positive prediction is poor. A new bedside quantitative fetal fibronectin test showed potential additional value over the conventional qualitative test, but there is limited evidence on the combination with cervical length measurement.
  
  
  OBJECTIVE
  The purpose of this study was to compare quantitative fetal fibronectin and qualitative fetal fibronectin testing in the prediction of spontaneous preterm birth within 7 days in symptomatic women who undergo cervical length measurement.
  
  
  METHODS
  We performed a European multicenter cohort study in 10 perinatal centers in 5 countries. Women between 24 and 34 weeks of gestation with signs of active labor and intact membranes underwent quantitative fibronectin testing and cervical length measurement. We assessed the risk of preterm birth within 7 days in predefined strata based on fibronectin concentration and cervical length.
  
  
  RESULTS
  Of 455 women who were included in the study, 48 women (11%) delivered within 7 days. A combination of cervical length and qualitative fibronectin resulted in the identification of 246 women who were at low risk: 164 women with a cervix between 15 and 30 mm and a negative fibronectin test (<50 ng/mL; preterm birth rate, 2%) and 82 women with a cervix at >30 mm (preterm birth rate, 2%). Use of quantitative fibronectin alone resulted in a predicted risk of preterm birth within 7 days that ranged from 2% in the group with the lowest fibronectin level (<10 ng/mL) to 38% in the group with the highest fibronectin level (>500 ng/mL), with similar accuracy as that of the combination of cervical length and qualitative fibronectin. Combining cervical length and quantitative fibronectin resulted in the identification of an additional 19 women at low risk (preterm birth rate, 5%), using a threshold of 10 ng/mL in women with a cervix at <15 mm, and 6 women at high risk (preterm birth rate, 33%) using a threshold of >500 ng/mL in women with a cervix at >30 mm.
  
  
  CONCLUSIONS
  In women with threatened preterm birth, quantitative fibronectin testing alone performs equal to the combination of cervical length and qualitative fibronectin. Possibly, the combination of quantitative fibronectin testing and cervical length increases this predictive capacity. Cost-effectiveness analysis and the availability of these tests in a local setting should determine the final choice.
authors.affiliation: Department of Obstetrics & Gynecology, Academic Medical Centre, Amsterdam, The Netherlands. Electronic address: m.m.bruijn@amc.uva.nl.
authors.forename: Merel M C
authors.initials: MM
authors.lastname: Bruijn
authors.affiliation: Department of Obstetrics & Gynecology, Academic Medical Centre, Amsterdam, The Netherlands; Department of Obstetrics & Gynecology, VU University Medical Centre, Amsterdam, The Netherlands.
authors.forename: Esme I
authors.initials: EI
authors.lastname: Kamphuis
authors.affiliation: Department of Obstetrics & Gynecology, University Hospital Basel, Basel, Switzerland.
authors.forename: Irene M
authors.initials: IM
authors.lastname: Hoesli
authors.affiliation: Department of Obstetrics & Gynecology, University Hospitals of Geneva and Faculty of Medicine, Geneva, Switzerland.
authors.forename: Begoña
authors.initials: B
authors.lastname: Martinez de Tejada
authors.affiliation: Department of Obstetrics & Gynecology, Hospital St Jan, Bruges, Belgium.
authors.forename: Anne R
authors.initials: AR
authors.lastname: Loccufier
authors.affiliation: Department of Obstetrics & Gynecology, University Hospital of Marburg, Germany.
authors.forename: Maritta
authors.initials: M
authors.lastname: Kühnert
authors.affiliation: Department of Obstetrics & Maternal-Fetal Medicine, Medical University Vienna, Vienna, Austria.
authors.forename: Hanns
authors.initials: H
authors.lastname: Helmer
authors.affiliation: Department of Obstetrics & Maternal-Fetal Medicine, Medical University Vienna, Vienna, Austria.
authors.forename: Marie
authors.initials: M
authors.lastname: Franz
authors.affiliation: Department of Obstetrics & Gynecology, Maxima Medical Centre, Veldhoven, The Netherlands.
authors.forename: Martina M
authors.initials: MM
authors.lastname: Porath
authors.affiliation: Department of Obstetrics & Gynecology, Academic Medical Centre, Amsterdam, The Netherlands; University Medical Centre Utrecht, Utrecht, The Netherlands.
authors.forename: Martijn A
authors.initials: MA
authors.lastname: Oudijk
authors.affiliation: Department of Obstetrics & Gynecology, Antwerp University Hospital, Antwerp, Belgium.
authors.forename: Yves
authors.initials: Y
authors.lastname: Jacquemyn
authors.affiliation: Department of Neonatology, University Children's Hospital Basel, Switzerland.
authors.forename: Sven M
authors.initials: SM
authors.lastname: Schulzke
authors.affiliation: Department of Obstetrics & Gynecology, University Hospital Basel, Basel, Switzerland.
authors.forename: Grit
authors.initials: G
authors.lastname: Vetter
authors.affiliation: Department of Obstetrics & Gynecology, Hospital St Jan, Bruges, Belgium.
authors.forename: Griet
authors.initials: G
authors.lastname: Hoste
authors.affiliation: Clinical Chemistry and Hematology, University Medical Centre Utrecht, Utrecht, The Netherlands.
authors.forename: Jolande Y
authors.initials: JY
authors.lastname: Vis
authors.affiliation: Department of Obstetrics & Gynecology, Academic Medical Centre, Amsterdam, The Netherlands.
authors.forename: Marjolein
authors.initials: M
authors.lastname: Kok
authors.affiliation: The Robinson Research Institute, School of Pediatrics and Reproductive Health and The South Australian Health and Medical Research Institute, University of Adelaide, Adelaide, Australia.
authors.forename: Ben W J
authors.initials: BW
authors.lastname: Mol
authors.affiliation: Department of Obstetrics & Gynecology, Academic Medical Centre, Amsterdam, The Netherlands.
authors.forename: Gert-Jan
authors.initials: GJ
authors.lastname: van Baaren
mesh_terms: D000328:Adult; D054791:Cervical Length Measurement; D003362:Cost-Benefit Analysis; D005060:Europe / Q000453:epidemiology; D005260:Female; D005353:Fibronectins / Q000378:metabolism*; D006801:Humans; D016015:Logistic Models; D007752:Obstetric Labor, Premature / Q000000981:diagnostic imaging / Q000378:metabolism; D011237:Predictive Value of Tests; D011247:Pregnancy; D047928:Premature Birth / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000378:metabolism; D011446:Prospective Studies; D018570:Risk Assessment; D014621:Vagina / Q000737:chemistry; D055815:Young Adult
chemical_list: C403421:FFN protein, human; D005353:Fibronectins
keywords: cervical length; fetal fibronectin; prediction; predictive value; preterm birth; threatened preterm labor