Preeclampsia Ratio (sFlt-1/PlGF) Evaluation for Clinical and Obstetrical Guidance

Preeclampsia is a hypertensive disorder of pregnancy associated with placental insufficiency and is one of the major important of prematurity and maternal mortality worldwide. It complicates 2 to 7% of pregnancies. It is currently considered that preeclampsia is associated with maternal endothelial dysfunction induced by the release into the maternal circulation of excess placental factors (such as sFLT-1 a soluble receptor for VEGF and PlGF). There is currently no curative treatment, and only childbirth and delivery of the placenta alleviate the mother's symptoms. Moreover, the evolution from case with mild symptoms to a severe case of preeclampsia is often is often rapid and difficult to anticipate. Therefore, it is recommended to manage patients with preeclampsia in hospital and cases of suspected preeclampsia are usually admitted in prenatal units. Each year thousands of patients are hospitalized for surveillance and blood/urine analysis to rule out the diagnosis of preeclampsia. A biological test to predict preeclampsia would therefore be of particular interest in order to:

• identify patients without preeclampsia and therefore void costs and iatrogenic complications related to unnecessary hospitalization
• identify patients at high risk of maternal and perinatal complications in order to anticipate in utero transfer, optimize maternal and fetal surveillance and administrate steroids.

It has recently been demonstrated that sFLT-1 and PlGF have a high predictive value for the diagnosis and the prediction of preeclampsia, but the interest of introducing these markers in clinical practice has not been demonstrated yet. The diagnostic and predictive value of the sFlt-1/PlGF ratio in patients at risk of placenta-related disorders has been shown in the recent literature and estimation of the sFlt-1/PlGF ratio has become an additional tool in the management of these disorders, primarily PE. This ratio can distinguish the patients that develop maternal or perinatal complications in the next 7-14 days from those with uncomplicated pregnancy. Women with an sFlt-1/PlGF ratio<38 do not have PE at the time of the test and in all likelihood will not develop PE for at least 1week; it is thereby of great value for reassuring the clinician and the patient. Up to 80% of patients are supposed to be in this patient group; therefore, clinicians are able to exclude the majority of patients and focus on those who need more attention and care. On contrary women with a sFlt-1/PlGF ratio > 38 and more specifically those with a ratio over 85 are highly likely to develop preeclampsia and should be managed according to local practice/guidelines. Thus the use of such predictive tool appear very promising but its interest has not been demonstrated in prospective intervention studies.

The aim of the PRECOG study is to determine in a prospective interventional randomized study whether the implementation of a predictive test based on the sFLT-1/PlGF ratio improves perinatal care and reduces costs, in patients with suspected preeclampsia before 35 WG. costs, in patients with suspected preeclampsia before 35 WG.