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“Recent Vaginal Exam” No Longer a Contraindication to Fetal Fibronectin Sampling

A Prospective Study [19A]

Swancoat, Steven

Obstetrics & Gynecology: May 2016 - Volume 127 - Issue - p 16S
doi: 10.1097/01.AOG.0000483312.42509.d3
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INTRODUCTION: 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.

Wyckoff Heights Medical Center, New York, NY

Financial Disclosure: The author did not report any potential conflicts of interest.

© 2016 by The American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.