Interest of a Vaginal Swab in Detection of Placental Alpha-Microglobulin-1 in the Prediction of Preterm Birth

Overview

Preterm labor is the first cause of hospitalization during the pregnancy, and at the origin of more than 60 000 births before 37 weeks of amenorrhea every year in France. It is however difficult to predict if a patient consulting in emergencies with symptoms of preterm labor, will give birth prematurely or not. Current diagnostic tools to identify patients with high risk of premature delivery in 7 days are insufficient because of their low positive predictive value. Yet the neonatal complications in case of premature delivery are important, with respiratory distress syndrome, hyaline membrane disease, necrotizing enterocolitis, intraventricular hemorrhage and post-natal death. Recent studies suggested that the detection of the placental alpha microglobulin 1 (PAMG-1) in the vaginal secretions, by Partosure® test at the women presenting symptoms of preterm labor with intact membranes would indicate that a premature spontaneous delivery could arise in 7 days with a good positive predictive value.The test is interesting all the more as the repetition of the prenatal cures of corticosteroids, aiming at the fetal lung maturation, is this day more recommended and as the beneficial effect takes place within 24 hours in 7 days following their administration. It seems thus essential to make studies to specify the interest of this test at the patients presenting a preterm labor. This study aims at estimating the diagnostic performance of the test of detection of PAMG-1 in the prediction of a delivery in 7 days, at the patients presenting symptoms of preterm labor.

Preterm labor is the first cause of hospitalization during the pregnancy and complicates of a premature delivery in about 30 % of the cases during single pregnancy. It is about a clinical situation arising between 22 and 36 amenorrhea weeks (SA) + 6 days, which are observed the cervical modifications and the uterine contractions confirmed by an ultrasound measure with cervical length ≤25mm.The main complication of the threat premature delivery (MAP) is the premature birth, which is an essential factor of perinatal morbidity and is the second cause of death before the age of 5 years. The measure of cervical length with ultrasound and the detection of the fetal fibronectin were estimated to identify the patients with risk of spontaneous premature delivery, however their capacity to discriminate these patients is insufficient (predictive value is positive of 20 %). It thus seems necessary to find a diagnostic alternative more relevant.The prenatal corticosteroid therapy is recommended for all the patients at risk of premature delivery in 7 days between 24 and 34 SA. Indeed the maximal profit of corticoids arises when the delivery occurs between 12 hours and 7 days following their administration, with a significant reduction in neonatal period the hyaline membrane diseases (50 %), intraventricular hemorrhage, necrotizing enterocolitis and deaths (40 %). Thus corticosteroids establishes the most important treatment in the prematurity.However, the beneficial effect of the corticosteroid therapy decreases if the birth arises beyond 7 days after the administration. So the efficiency of a complete cure of corticoids in the prevention of the neonatal respiratory morbidity is in connection with deadline between the administration and the delivery. The challenge consists in administering the cure of corticoids in 7 days preceding the birth to benefit from the maximal neonatal profit. Besides, the repetition of the cures of corticoids could be responsible for noxious effects on the future of the future adult by distorting the growth of the child and its cognitive future, by increasing the risk of obesity or insulin resistance, as well as the cardiovascular risk in the adulthood.The capacity to discriminate between the patients who are going to give birth prematurely in 7 days so answers a double objective: allow the implementation of an effective and beneficial preventive treatment for the newborn child and avoid treatments and inconvenient hospitalizations, generators of unwanted effects and useless spending.A recent study estimates the interest of an interesting molecule, the placental alpha microglobulin 1 (PAMG-1), in this diagnostic approach. She concludes that the detection of PAMG-1 by a vaginal taking is the best test to predict spontaneous delivery in 7 days compared with the measure of the cervical length by transvaginal ultrasound and the test of fetal fibronectin. If the performance of the test is validated by the study, the coverage of the patients would be optimized with less frequent and less long hospitalizations, as well as a decrease of treatments pointlessly prescribed at the patients not giving birth finally prematurely (tocolytics, corticoids). For those giving birth prematurely, corticoids could be administered for an optimal deadline to obtain the maximal profit for the newborn child.