At a Glance
Why Get Tested?
To help evaluate a pregnant woman's risk of preterm delivery
When to Get Tested?
A cervical or vaginal fluid sample
Test Preparation Needed?
None, but to reduce the chance of a false result, avoid sexual intercourse for 24 hours prior to sample collection.
The Test Sample
What is being tested?
Fetal fibronectin (fFN) is a glycoprotein that can be used to help predict the short term risk of premature delivery. fFN is produced at the boundary between the amnionic sac (which surrounds the baby) and the lining of the mother's uterus (the decidua) in an area called the uteroplacental (or choriodecidual) junction. Fetal fibronectin is largely confined to this junction and is thought to help maintain the integrity of the boundary. fFN is normally detectable in cervicovaginal fluid during early pregnancy, and in a normal pregnancy it is no longer detectable after 24 weeks. However, it reappears and is again detectable after about 36 weeks.
According to the American College of Obstetricians and Gynecologists (ACOG), a normal pregnancy is 40 weeks with a woman going into labor between 37 and 42 weeks. Finding fFN in cervicovaginal fluids after 36 weeks is not unusual as it is often released by the body as it gets ready for childbirth. The elevated fFN found in vaginal fluids early in pregnancy may simply reflect the normal growth and establishment of tissues at the uteroplacental junction with levels falling when this phase is complete. What is known is that fFN should not be detectible between 22 and 35 weeks of pregnancy. Elevated levels during this period reflect a disturbance at the uteroplacental junction and have been associated with an increased risk of preterm labor and delivery.
How is the sample collected for testing?
A Dacron swab is used to take a sample of cervical or vaginal fluid from the posterior portion of the vagina or from the area just outside the opening of the cervix.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
Anything that physically disturbs the cervix or uterus has the potential to elevate fFN levels. Therefore, cervicovaginal fluid samples should be collected before any physical examinations. Lubricants, lotions, soaps, and douches should be avoided. Semen may contain enough fFN to create a positive test result, so sexual intercourse should also be avoided within 24 hours of sample collection.
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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
Sources Used in Current Review
March of Dimes. Fetal Fibronectin (fFN), A Test for Premature Delivery. Available online at http://www.marchofdimes.com/professionals/14332_1149.asp through http://www.marchofdimes.com. Accessed November 2009.
March of Dimes. About Prematurity, Complications in the Newborn. Available online at http://www.marchofdimes.com/prematurity/index_about_6306.asp through http://www.marchofdimes.com. Accessed November 2009.
American College of Obstetricians and Gynecologists (ACOG). Management of Preterm Labor. ACOG Practice Bulletin, number 43, May 2003 (reaffirmed 2008).
HologicTM. Facts About Fetal Fibronectin Testing.
HologicTM. Frequently Asked Questions: Preterm Birth and Fetal Fibronectic Testing.
Mayo Clinic. Fetal Fibronectic Test. How you prepare. Available online at http://www.mayoclinic.com/health/fetal-fibronectin/MY00128/DSECTION=how-you-prepare through http://www.mayoclinic.com. Accessed November 2009.
Mayo Clinic. Preterm labor: Take prevention seriously. Available online at http://www.mayoclinic.com/health/preterm-labor/PR00118 through http://www.mayoclinic.com. Accessed November 2009.
Clinical Laboratory News. Fetal Fibronectin October 2008: Volume 34, Number 10. Available online at http://www.aacc.org/publications/cln/2008/october/Pages/series_1008.aspx through http://www.aacc.org.
Sources Used in Previous Reviews
Thomas, Clayton L., Editor (1997). Taber's Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition].
Pagana, Kathleen D. & Pagana, Timothy J. (2001). Mosby's Diagnostic and Laboratory Test Reference 5th Edition: Mosby, Inc., Saint Louis, MO.
Palkhivala, A.(2002 October 23). AAFP: Foetal Fibronectin Testing May Reduce Need for Transfer to Tertiary Care Centers. Doctor's Guide Global Edition [On-line information]. Available online at http://www.pslgroup.com/dg/221052.htm through http://www.pslgroup.com.
A Diagnostic Test for Accessing the Risk of Preterm Delivery. fFN Professional Home Page, Adeza [On-line information from company]. PDF available for download at http://www.ffntest.com.
Fetal Fibronectin (fFN): A Test for Preterm Delivery. March of Dimes, Professionals and Researchers, Quick Reference and Fact Sheets [On-line information]. Available online at http://www.marchofdimes.com/professionals/681_1149.asp through http://www.marchofdimes.com.
(2000 Spring). Cervical-Vaginal Fetal Fibronectin (fFN) Testing to Predict Preterm Labor & Delivery. University of Washington Dept of Laboratory Medicine Perspectives [Online community newsletter]. PDF available for download at http://depts.washington.edu/labweb/test/pers/perspr00.pdf through http://depts.washington.edu.
High Risk Pregnancy, Preterm Labor. University of Utah Health Sciences Center [On-line information]. Available online at http://www.uuhsc.utah.edu/healthinfo/pediatric/hrpregnant/ptl.htm through http://www.uuhsc.utah.edu.
(2002 April 25, Updated). Fetal Fibronectin for the Prediction of Preterm Labor. Institute for Clinical Systems Improvement, Knowledge Resources Technology Assessment Report [On-line information]. Available online at http://www.icsi.org/knowledge/detail.asp?catID=107&itemID=281 through http://www.icsi.org.
Goldenberg, R. (2002 November). High-Risk Pregnancy Series: An Expert's View, The Management of Preterm labor [On-line information]. Available online through http://www.acog.org/.
(2002 July). FFN, A Test to Aid in the Assessment of Preterm Delivery Risk. Adeza Biomedical Fetal Fibronectin Enzyme Immunoassay and Rapid fFN for the Tli System [On-line information]. PDF available for download at http://www.ffntest.com.
Mark, P. et. Al. (2000 January). ICSI Medical Brief, Fetal Fibronectin for the Prediction of Preterm Labor. ICSI Technology Assessment Report, TA #47 [On-line report]. Available online at http://www.icsi.org/knowledge/detail.asp?catID=107&itemID=281 through http://www.icsi.org.
Von Der Pool, B. (1998 May 15). Preterm Labor: Diagnosis and Treatment. AAFP American Family Physician [On-line Journal]. Available online at http://www.aafp.org/afp/980515ap/vonderp.html through http://www.aafp.org.
Pagana, Kathleen D. & Pagana, Timothy J. (© 2007). Mosby's Diagnostic and Laboratory Test Reference 8th Edition: Mosby, Inc., Saint Louis, MO. Pp 445-446.
Wyatt, S. and Rhoads, S. (2006 September 19). A Primer on Antenatal Testing for Neonatal Nurses: Part 1. Tests Used to Predict Preterm Labor. Medscape from Adv Neonatal Care. 2006;6(4):175-180 [On-line information]. Available online at http://www.medscape.com/viewarticle/543521 through http://www.medscape.com. Accessed on 2/28/07.
(© 2007). Fetal Fibronectin (fFN): A Test for Preterm Delivery. March of Dimes [On-line information]. Available online at http://www.marchofdimes.com/professionals/681_1149.asp through http://www.marchofdimes.com. Accessed on 2/27/07.
(© 2007). What is Preterm Labor. The American College of Obstetricians and Gynecologists (ACOG) [On-line information]. Available online at http://www.acog.org/publications/patient_education/bp087.cfm through http://www.acog.org. Accessed on 3/4/07.
FullTerm, The Fetal Fibronectin Test. ADEZA [On-line information]. Available online at http://www.ffntest.com/html/HCP_US_FullTerm.htm through http://www.ffntest.com. Accessed on 3/3/07.