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Test Name:
Fetal Fibronectin, Cervicovaginal Secretions
- SBMF No:
28095 - Performance Lab Name:
Hematology - Test Mnemonic:
FFN - ABN:
Not required - CPT Code:
82731 - LOINC Code:
20404-0 - Also Known As:
fFN
Fibronectin, Fetal
Preterm Labor Test - Spec Type:
Cervicovaginal Secretions - Spec Container:
Specimen Collection Kit (Cytyc/Hologic) - Alt Spec Type:
Vaginal Secretions - Alt Spec Container:
Specimen Collection Kit (Cytyc/Hologic) - Pref Vol:
Sample collected with Dacron® swab from collection kit immersed in transport tube containing extraction buffer - Fasting:
No - Patient Prep:
Patient should meet the following criteria:
Amniotic membranes are intact
Cervical dilatation is minimal (less than 3.0 cm)
Sampling performed no earlier than 25 weeks of gestation; and no later than 35 weeks of gestation - Spec Collect:
Collect using Specimen Collection Kit (Cytyc/Hologic):
– During sterile speculum examination, lightly rotate swab across posterior fornix of the vagina, or the ectocervical region of the external cervical os, to absorb cervicovaginal secretions
– Remove swab and immerse Dacron® tip in buffer
– Break shaft (at the score) even with top of tube
– Align the shaft with the hole inside the tube cap and push down tightly over the shaft, sealing the tube - Spec Process:
Immediately after collection, place specimen in container of ice slush (ice and water mixture) or refrigerate
Transport to SBMF on day of collection - Spec Store Transport:
Refrigerated - Spec Stability:
3 days refrigerated (2-8°C) - Spec Reject:
Sample using sample device other than the Specimen Collection Kit (Cytyc/Hologic)
Received more than 3 days after sampling date
Frozen or received at temperatures greater than 25°C - Methodology:
Solid Phase Immunosorbent - Use:
Aid in assessing the risk of pre-term delivery - Clinical Significance:
Fetal fibronectin, a glycoprotein, is a major component of the extracellular matrix of the membranes of the amniotic sac. Secreted by fetal membranes and found in the junction between the chorion and the decidua (the choriodecidual junction), fetal fibronectin acts as a kind of “glue” that binds the placenta to the uterus. A clinically proven biochemical marker, fetal fibronectin is an important and reliable predictor of the risk of preterm delivery. The level of fetal fibronectin in the cervicovaginal secretions of pregnant women is highly correlated with preterm labor.
In a normal pregnancy, the concentration of fetal fibronectin in the cervicovaginal fluid is less than 50 ng/mL from 22 to 35 weeks’ gestation. The presence of 50 ng/mL or more of fetal fibronectin in a gravida’s cervicovaginal secretions at this stage of gestation is associated with an increased likelihood of preterm delivery. Concentrations of fetal fibronectin less than 50 ng/mL are associated with pregnancy continuance. In symptomatic women, the fFN test has a negative predictive value of 99.2% for delivery within the next 14 days and 99.5% for delivery in the next 7 days. A single negative test indicates that there is a very low risk of preterm delivery (less than 1%) within the next 14 days.
In asymptomatic women, a single negative fetal fibronectin test obtained at 24 weeks’ gestation has a negative predictive value of:
99.7% for preterm delivery before 28 weeks’ gestation
96.3% for preterm delivery before 35 weeks’ gestation
A negative test makes it possible to:
Alleviate patient uncertainty
Reduce or eliminate interventions
Reassure patients that they are highly unlikely to deliver at or before 34 weeks’ gestation
Eliminate costs associated with hospital admissions and transportation
Avoid unnecessary reduction in or cessation of work
In contrast, 31.7% of asymptomatic women with a positive test result at 24 weeks’ gestation will deliver before 35 weeks’ gestation.
Care decisions that should be considered following a positive test include:
Increased intensity of prenatal observation
Evaluation of other risk factors
Increased patient education
Possible earlier intervention
Patient benefits after a positive test include:
Increased surveillance and management options
Preparation for optimal neonatal care - Reference Range:
Negative - Additional Test Info:
Limitations of Procedure:
The fetal fibronectin result should not be interpreted as absolute evidence for the presence or absence of a process that will result in delivery in less than or equal to 7 or 14 days from specimen collection in symptomatic women or delivery in less than or equal to 34 weeks, 6 days in asymptomatic women evaluated between 22 weeks, 0 days and 30 weeks, 6 days of gestation. A positive fetal fibronectin result may be observed for patients who have experienced cervical disruption caused by, but not limited to, events such as sexual intercourse, digital cervical examination, or vaginal probe ultrasound. The fetal fibronectin result should always be used in conjunction with information available from the clinical evaluation of the patient and other diagnostic procedures such as cervical examination, cervical microbiological culture, assessment of uterine activity, and evaluation of other risk factors. - Day Run:
Sun-Sat (daily) - Time Run:
Multiple runs - Time Reported:
Within 8 hours - Test Type:
OBSTETRIC-NEONATAL
