[In utero treatment of twin-to-twin transfusion syndrome].

Twin-to-twin transfusion syndrome (TTTS) is a serious complication of monochorionic twin pregnancies in which an imbalance in blood flow between the twins is caused by vascular anastomoses in the placenta. TTTS affects 10 to 15% of these monochorionic pregnancies and can lead to high perinatal mortality if left untreated. The Quintero classification, introduced in 1999, helps stratify the severity of TTTS into five stages, thereby facilitating clinical decision-making. Laser photocoagulation of placental anastomoses, a technique developped in the 2000s, has become the standard of care for severe stages, with significantly improved survival rates. Although this procedure is minimally invasive for the mother, it is not without risks to the pregnancy. Other strategies include amniodrainage to relieve maternal symptoms, expectant management in early stages, and sometimes selective termination of pregnancy. Twins often require intensive neonatal care and multidisciplinary follow-up to manage long-term complications. This complex syndrome requires management in specialized centers with expertise in fetal medicine.