Comparison of a novel test for placental alpha microglobulin-1 with fetal fibronectin and cervical length measurement for the prediction of imminent spontaneous preterm delivery in patients with threatened preterm labor

Abstract

Objective: PartoSure is a bedside test for the prediction of time-to-spontaneous preterm delivery by the detection of placental alpha microglobulin-1 (PAMG-1). The objectives of this study were to further determine the test’s efficacy in predicting delivery within 7 or 14 days from testing, and to compare it with fetal fibronectin (fFN) and cervical length (CL) measurement by transvaginal ultrasound. Study design: The study population consisted of 203 consecutively recruited women with singleton pregnancies between 20^0/7 and 36^6/7 weeks of gestation with symptoms of preterm labor, clinically intact membranes, and cervical dilatation of ≤3 cm. PartoSure and CL were performed on all patients and the test-to-spontaneous-delivery interval was calculated. In a sub-segment of patients, the QuikCheck fFN test was used. Results: The sensitivities for PartoSure (n=203), fFN (n=66), and CL (n=203) for predicting imminent spontaneous preterm delivery within 7 days were 80%, 50%, and 57%, respectively. The specificities were 95%, 72%, and 73% for PartoSure, fFN and CL, respectively. The NPVs were 96%, 87%, and 89% for PartoSure, fFN and CL, respectively. The PPVs were 76%, 29%, and 30% for PartoSure, fFN and CL, respectively. Conclusion: PAMG-1 detection by PartoSure is the single best predictor of imminent spontaneous delivery within 7 days compared to fFN and CL. In settings where CL is used as an initial screen, PartoSure has the greatest clinical utility in patients with CL between 15 and 35 mm. In situations where CL is not an initial screen, PartoSure is the most accurate test compared to fFN and CL.