Threatened Preterm labor (TPL) accounts for 1,000's of unnecessary yearly admissions with an average cost of $14,000 per patient. With a 98% specificity, Fetal Fibronectin (FFN) is a very powerful test that can safely rule out threatened preterm labor with nearly 99% accuracy for up to two weeks. However the company states that a “recent vaginal examination” is a contraindication as it may lead to a false positive. Yet they submit no clinical research to support this statement.METHODS:
Two FFN sampling were collected from 18 patients whom met the indicated criteria for TPL. Criteria included single gestation between 24–33 6/7 weeks, no sexual intercourse or vaginal exam within past 48 hours, or showing signs or symptoms of preterm labor. Patients were initially sampled for FFN, vaginal exam performed, following a second FFN sampling was collected. The two samples were then compared against each other and patients were followed until they went into labor.RESULTS:
Of the 18 patients, (14) patients tested FFN neg/neg. (2) positive/neg, (1) neg/positive and (1) positive/positive, Of 15 initial neg results, only one tested positive after vaginal exam, yielding a 6% false positive. Of three who tested initially positive, two retested neg, Neither delivered before 37 weeks.CONCLUSION:
Though a small sample size, study shows “recent vaginal exam” prior to FFN sampling yields a very low rate for false positives and should no longer be considered a contraindication to testing. Furthermore with an initial positive test result, a repeat test should be performed for true negative.