Fetal fibronectin in cervical and vaginal secretions
Fetal fibronectin fFN is a large glycoprotein located in the extracellular matrix of the choriodecidual junction between the maternal decidua and the fetal membranes. It is an adhesive glycoprotein that crosslinks collagen and binds cells together. Some research has suggested that it plays a role in implantation. By 37 weeks gestation, fFN becomes more heavily glycosylated, loses its adhesive properties and is again detectable in cervicovaginal secretions.
Perinatal Testing | fFN Test | Fetal Fibronectin| Hologic
Fetal fibronectin fFN is a fibronectin protein produced by fetal cells. It is found at the interface of the chorion and the decidua between the fetal sac and the uterine lining. It can be thought of as an adhesive or "biological glue" that binds the fetal sac to the uterine lining. Fetal fibronectin "leaks" into the vagina if a preterm delivery is likely to occur and can be measured in a screening test.
When you are 22 to 35 weeks pregnant and are having symptoms of premature labor; sometimes if you are at high risk, such as if you have had a previous preterm delivery or have a short cervix. A 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. Anything that physically disturbs the cervix or uterus has the potential to elevate fFN levels. Therefore, your healthcare practitioner should collect the sample before a pelvic examination or vaginal ultrasound. Semen may contain enough fFN to create a positive test result, so sexual intercourse should be avoided within 24 hours of sample collection.
Aetna considers the fetal fibronectin fFN immunoassay test medically necessary for evaluating symptomatic pregnant women at high-risk for preterm delivery see background section for selection criteria. Repeat fFN immunoassay test is considered medically necessary if members remain symptomatic two or more weeks after a previous negative test. Aetna considers human chorionic gonadotrophin and phosphorylated insulin-like growth factor binding protein-1 in cervico-vaginal fluid experimental and investigational for evaluating pregnant women at high-risk for preterm delivery because their effectiveness for this indication has not been established. Aetna considers salivary estriol SalEst test experimental and investigational because the test results are not available rapidly enough to assist in decisions concerning the immediate care of the member. Aetna considers proteomic biomarkers e.