Examen du placenta

The human placenta is a mysterious organ between the mother and the foetus. It is an essential organ for gas and nutriments exchange leading to foetal growth and development. On the other hand, the placenta may be at the origin of severe maternal or foetal diseases. Before birth, the placenta is explored by ultrasounds, flow velocity and chorionic villous sample. After delivery, the placenta is an easily available specimen to understand perinatal diseases. The entire placenta should be grossly examined in the delivery room by the midwife and/or the obstetrician. Pathological examination of the placenta is indicated in case of maternal, foetal or placental abnormalities. This examination has to be integrated with the obstetrical and neonatal data. However, the placenta is usually under-evaluated and insufficiently used for the diagnosis of placental disease. The characterisation of placental diseases may provide crucial information for the etiological diagnosis of prematurity, intrauterin growth retardation, foetal demise, neurodevelopmental impairment. In case of twin pregnancy, the type of twinning can be identified and pathological aspects of twin pregnancy can be studied. The examination can identify placental conditions that can be recurrent or inherited in order to adequate treatment and preventive measures during subsequent pregnancies. Placental examination may have medicolegal aspect for example concerning the aetiology of long term neurodevelopmental sequelae. New clinicopathological entities such as inflammatory foetal response of the placenta and fetal thrombotic vasculopathy have been recently clarified. A pertinent placental examination integrated with a multidisciplinary approach with obstetricians and paediatricians should identify new clinicopathological entities and provide a better understanding of pathophysiological mechanisms in order to propose new treatments in severe and often recurrent perinatal diseases.