Does the Performance of the Ductus Venosus Doppler at 16 Weeks Allow to Increase the Screening of the Twin-twin Transfusion Syndrome and to Reduce the Neonatal Mortality?

Studies shows that the realization of the Ductus venosus Doppler may improve the screening of the twin-twin transfusion syndrome. In this study, we want to compare the outcome of monochorial pregnancy when this Doppler was performed during the ultrasound at16 weeks, and when it wasn't. In order to do that, we will compile past reports (January 2015/ January 2018) of all monochorial pregnancy handled in the hospital of Montpellier and Kremlin Bicêtre. We will establish if the Doppler was done or not, if the twin-twin transfusion syndrome appears and the neonatal outcome.