Preeclampsia is a disease which originates in the placenta and is specific to human pregnancy. It is one of the main causes of maternal and perinatal morbidity and mortality. The introduction of assays for angiogenic and anti-angiogenic markers reflecting placental dysfunction, which lies at the root of preeclampsia, is a turning point in the management of women with suspected preeclampsia or with an atypical form of the disease. The sFlt1/PlGF ratio assay, which has been covered by health insurance since July 2019, is a valuable diagnostic aid : the disease can be ruled out, with a high negative predictive value, when the ratio is low, thus avoiding unnecessary hospital admission and premature delivery. A high ratio can help to confirm the diagnosis of preeclampsia, albeit with a lower positive predictive value.