The review of results of foetal fibronectin at the Royal Cornwall Hospital Treliske

Abstract

The manufacturer of a popular qualitative fFN assay, changed to using a quantitative assay following results from EQUIPPE study. The objective of our study was to compare our hospital data collated from our qualitative fFN assay with EQUIPPE’s data, with a view to establish its validity in our hospital. We undertook a retrospective study over a 22-month period to review the data of 432 preterm pregnant women at less than 34 weeks of gestation, who presented to the labour ward with symptoms of threatened preterm labour warranting a fFN test. None of the patient with results between 11 and 199 ng/mL delivered within 7 days. However, there was a rise in percentage of delivery at higher levels. For example, 73% of patients with levels greater or equal to 500 ng/mL delivered within 7 days. Our results are comparable with those of the EQUIPPE study. This has led to changes that could potentially save our hospital money. Impact statement What is already known on this subject? The fFN test is a well validated test used to diagnose a preterm delivery. Most units are changing from the qualitative assays that just show positive or negative results to quantitative assays that give specific numeric values. Manufacturers give a numeric range for positive and negative results. What do the results of this study add? Although our study is local to our population, our findings show that potentially more money could be saved and fewer women separated from their families, if the negative level of the fFN test is increased (following a review of their local practice). What are the implications of these findings for clinical practice and/or further research? More units should review or audit their fFN results and choose what levels to use as a cut off for the test locally. More importantly, a multicentre research is needed to validate if the negative level needs increasing from 49 ng/mL.