Stratégie de diagnostic prénatal et prise en charge des pathologies liées aux grossesses multiples

In the first trimester of pregnancy, ultrasound is crucial to screen for aneuploidies based on nuchal translucency, to diagnose major birth defects, and to establish chorionicity. Indeed prenatal diagnosis strategies as well as obstetrical management options are largely based on placental type. In the second trimester, maternal serum screening is not as effective, and ultrasound screening is more difficult in twins than in singletons. When a severe abnormality in found in one twin, selective termination of pregnancy may be considered. This technique is safe in dichorionic twins, but hazardous in monochorionic pregnancies. Selective termination in dichorionic twins is safer in the first trimester, underscoring the need for early prenatal diagnosis in twins. Monochorionic twin pregnancies carry specific risks, such as the twin to twin transfusion syndrome, which can be treated by endoscopic photocoagulation of intertwin anastomoses in the severe early onset cases, or by amnioreduction in milder cases.