FFN (Fetal Fibronectin) Testing (PTL), Preterm Labor and (PTD) Preterm Delivery

The overall risk of preterm labor for the general obstetrical population is 7%. Some risk factors include: a history of preterm delivery, multiple gestations, cervical surgery and multiple abortions. Most patients who have PTL have no risk factors for preterm labor.

The uterus normally contracts as the pregnancy grows. Only if excessive and persistent contractions cause a change in the cervix can the term preterm labor be used. In addition to a physical examination of the dilation, length and consistency of cervix, an ultrasound can be used to measure the internal cervical length and dynamic cervical changes.

The FFN is the best independent test to predict preterm labor. The test can be performed between 24 weeks to before 35 weeks. The test can only be done with intact membranes and nothing per vagina in the past 24 hours like gel, semen, blood or a cerclage. The cervix also needs to be < 3 cm dilated. A negative FFN test is excellent news since you have a 96% to 98% confidence that you will not deliver in the next 2 weeks. A positive FFN is less helpful since only 1/3 of women will deliver before 35 weeks.

The FFN test helps your medical team decide on your activity level, treatments, admission to the hospital or release from restrictions and follow-up tests. Fortunately, with the excellent neonatal care available today, babies born after 32 weeks generally have an excellent prognosis.

To perform an FFN test, a dry Q-tip will be swabbed in the vagina for 10 seconds and sent to the laboratory. The results are available within 2 hours if done in hospital and a report can be called for within 24 hours if sent in from the office. Please talk to your medical assistant or Irene regarding when to call our office so we can call the hospital for your result.

Summary of What the FFN result means:

A normal cervical length is generally greater than 3 cm. long on clinical examination and greater than 2.5 cms. by ultrasound. A 2 cm. cervix is actually normal in 85% of women but close follow-up is required to rule out the 15% that have preterm labor and not simple preterm contractions. Approximately 75% of multiparous women (women who have delivered full term babies before) will have slight cervical dilation by 32 weeks. If you cervix is < 2 cm. in length and you are having PTL symptoms/contractions, then the risk of an actual preterm delivery is increased by 8xs.

We recommend a 24 week baseline sonogram for our patients with a history of preterm delivery.