A positive fetal fibronectin test with a closed cervix can be confusing. One finding suggests potential early labor, while the other indicates the pregnancy is being maintained. This article clarifies what these findings mean and their implications.
What is Fetal Fibronectin?
Fetal fibronectin (fFN) is a protein that acts as a “glue,” attaching the amniotic sac to the uterine lining. Normally, fFN is found in cervicovaginal secretions during the first half of pregnancy and again as term labor approaches. Its presence between 22 and 34 weeks of gestation can indicate a disruption, suggesting an increased risk of preterm labor.
The fFN test is performed when preterm labor is suspected due to symptoms like contractions, pelvic pressure, or changes in vaginal discharge, or for individuals at high risk. A fluid sample is collected from the cervix or posterior vagina for laboratory analysis. A positive fFN result indicates an increased chance of preterm birth within seven to fourteen days, but it is not a definitive diagnosis of impending labor.
The Significance of a Closed Cervix
The cervix, the lower part of the uterus, remains long, firm, and closed to keep the developing fetus safely inside. This protective function is maintained throughout most of the pregnancy until labor approaches. A “closed cervix” means there is no measurable dilation or effacement, indicating the cervix has not yet begun to open or thin.
A closed cervix is generally a reassuring sign, suggesting the body is maintaining the pregnancy by keeping the uterine entrance sealed. In contrast, cervical changes like shortening (effacement) and opening (dilation) are physiological processes that occur as labor nears, allowing the baby to pass into the birth canal. These changes are strong indicators of impending labor, making a closed cervix a favorable finding in the context of preterm labor concerns.
Interpreting a Positive Result with a Closed Cervix
The combination of a positive fetal fibronectin test and a closed cervix can seem contradictory. This scenario does not necessarily mean immediate preterm labor, but rather an increased statistical risk that warrants closer observation. A positive fFN with a closed cervix suggests an underlying disruption at the maternal-fetal interface, even without overt cervical changes like dilation or effacement.
Several factors can lead to a positive fFN result even with a closed cervix. Minor, transient disruptions of the “glue” can occur without causing immediate cervical changes, triggered by activities like recent intercourse, a vaginal examination, or subtle uterine contractions. The presence of fFN serves as an early warning sign, indicating some stress on the body, even if the cervix has not yet visibly responded. It is a statistical marker of risk, not a guarantee of preterm birth. Healthcare providers consider the overall clinical picture, including reported symptoms, other risk factors, and cervical length measured by ultrasound.
Clinical Implications and Management
Following a positive fetal fibronectin test with a closed cervix, medical management typically involves a cautious approach focused on increased monitoring and specific recommendations. Healthcare providers often suggest more frequent prenatal visits to closely observe the pregnancy’s progression. Further cervical length measurements via transvaginal ultrasound may be performed, as a shorter cervical length combined with a positive fFN further increases the concern for preterm delivery.
Common recommendations include activity modification, such as avoiding strenuous activities, though strict bed rest is generally not advised. Patients are usually advised to avoid vaginal intercourse and douching. Education on recognizing the signs of preterm labor, such as persistent contractions, fluid leakage, or bleeding, is also provided, with instructions to report any such symptoms promptly.
If other risk factors are present or the clinical picture suggests progression towards preterm labor, medical interventions might be considered. These could include administering corticosteroids to accelerate fetal lung maturity or, in specific cases, progesterone supplementation. Management is individualized, taking into account the patient’s unique circumstances and the complete clinical assessment.