When should the fetal fibronectin test not be performed?

The fetal fibronectin test is a diagnostic tool used to assess the risk of preterm labor, specifically in women who present with symptoms of preterm labor. It measures the presence of fetal fibronectin, a protein that acts as a "glue" between the fetal membranes and the uterine wall. When this protein is found in the vaginal secretions, it is indicative of a higher risk of preterm birth.

Performing the test after recent intercourse or in the presence of vaginal bleeding can lead to false-positive results. This is because both intercourse and vaginal bleeding can introduce fetal fibronectin into the vaginal secretions, potentially skewing the test results toward indicating higher risk when it may not be accurate. Therefore, it is critical to avoid these conditions before the test to ensure the reliability of the results.

On the other hand, in situations such as after 24 weeks of gestation, in the presence of low amniotic fluid, or during active labor, the circumstances may alter the test's interpretability but do not disqualify its performance outright as does the presence of recent intercourse or bleeding.