This protein is located at the choriodecidual interface, between fetal membranes and the lining of the uterus. It acts as a kind of "glue " � that binds the fetus to the mother. The fFN test measures the protein "leaked " � through the cervix into the vagina in pregnancys final stages, as the fetus prepares for the birth process.
Normal range: negative.
Use
To predict the risk of preterm delivery in symptomatic patients, since identifying women with preterm contractions who will go on to deliver prematurely is an inexact process
To identify asymptomatic women, usually in a high-risk group (e.g., previous preterm delivery, multiple gestation), who are most likely to deliver preterm
Interpretation
Increased (Positive) In
Up to 40% of women with signs and symptoms deliver within the next 7 days.
A woman tested at 24 weeks is nearly 60 times more likely to deliver within the next 4 weeks compared with a woman with a normal fetal fibronectin test when taken between weeks 22 and 24. The test detects nearly two thirds of the preterm births that occur prior to 28 weeks.
Decreased (Negative) In
99.5% of women with signs and symptoms will not deliver within the next 7 days.
Less than 1% of women with identified risk factors will deliver before 28 weeks if they have a normal fetal fibronectin test result at 22 " �24 weeks.
Limitations
fFN results should not be interpreted as absolute evidence for the presence or absence of a process that will result in delivery in <14 days from specimen collection in symptomatic women or delivery in ≤34 weeks, 6 days in asymptomatic women evaluated between 22 weeks, 0 days and 30 weeks, 6 days of gestation.
A positive rapid fFN 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 rapid fFN 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 of a cervical microbiologic culture, assessment of uterine activity, and evaluation of other risk factors.
The assay has been optimized with specimens taken from the posterior fornix of the vagina or the ectocervical region of the external cervical os. Samples obtained from other locations should not be used.
Assay interference from the douches, white blood cells, red blood cells, bacteria, and bilirubin has not been ruled out.
Manipulation of the cervix may lead to false-positive results. Specimens should be obtained prior to digital examination or manipulation of the cervix.
Care must be taken not to contaminate the swab or cervicovaginal secretions with lubricants, soaps, or disinfectants (e.g., K-Y Jelly lubricant, Betadine disinfectant, Monistat cream). These substances may interfere with absorption of the specimen by the swab.
Patients with suspected or known placental abruption, placenta previa, or moderate or gross vaginal bleeding should not be tested for fFN.