Diagnosis and Management of Complicated Monochorionic Twins

Although monochorionic (MC) twins comprise only 20% of all twin pregnancies, the risk for fetal loss and long-term morbidity is significantly higher than dichorionic twins due to the presence of placental vascular anastomoses. MC twins are at risk for multiple unique complications including twin-twin transfusion syndrome, selective intrauterine growth restriction, twin anemia-polycythemia sequence, and twin reversed arterial perfusion sequence. Discordant anomalies can negatively impact the outcome for the normal cotwin. It is imperative that early determination of chorionicity is established such that the appropriate surveillance is in place to identify MC complications to optimize outcomes.