THE ROLE OF PARTOSURE™ TEST IN PREDICTING IMMINENT PRETERM BIRTH

INTRODUCTION An accurate risk assessment of preterm birth is clinically important in pregnancies with threatened preterm labor. This is particulary true with respect to both the administration of corticosteroids, as well as the transfer of patients to a tertiary care center capable of caring for the birth of premature infants. Clinical evaluation alone, with the measurement of cervical length and dilatation, are not sufficiently predictive of imminent delivery. Currently available biomarker tests, such as the detection of fetal fibronectin, have extramely poor predictive value form imminent delivery. The PartoSure™ test is a rapid, qualitative immunochromatographic test for the in vivo detection of placental alpha microglobulin-1 (PAMG-1) in vaginal secretions of pregnant women. PAMG-1 is a protein found in high concentrations in the amniotic fluid. METHODS We conducted a prospective observational study from March to June 2016. We enrolled 20 symptomatic patients between 24-34 week of gestation with singleton pregnancy, irregular uterine activity and/or lower abdominal pain and pelvic pressure, intact membranes, cervical length < 20 mm and funneling. Patients were initially managed according to the internal protocol: prophylactic corticosteroid betamethasone i.m. 12 mg/day for 2 days and primary tocolysis for 48 hours. 7 days after the therapy, we evaluated all the patients: 2 patients had delivered and 3 patients were excluded for premature rupture of membranes. In the final analysis, we included 15 patients. The PartoSure™ test was performed for these patients. The result was interpreted once two lines were visible, or after 5 min elapsed since the insertion of the test strip into the sample vial. The patients were divided in two groups: the test was positive for two patients (Group A) and was negative for 13 patients (Group B). All patients had been revaluated after 7 and 14 days from the execution of the test. RESULTS In group A, a patient delivered within 7 days, while the others delivered within 14 days from presentation. In group B, a patient delivered within 7 days, while 12 patients were still pregnant after 14 days. CONCLUSIONS In our study, the positive and negative predictive value of the PartoSure™ test seems to be high within 7 and 14 days (PPV 100%, NPV 92%). However, our conclusions are based on a small sample, so further studies are needed. If our results will be confirmed, the device could be considered an excellent test to rapidly assess the risk of preterm delivery within 7 or 14 days from time of collection of cervicovaginal sample in pregnant women with signs and symptoms of early preterm delivery, intact membranes and minimal expansion. A positive PartoSure™ test in these patients indicates with a high degree of accuracy that spontaneous preterm delivery will occur within 7 days. A negative result indicates that spontaneous preterm delivery within 14 days is highly unlikely.