Surveillance of monochorionic twins for detection of twin-twin transfusion syndrome and twin anemia polycythemia sequence: a North American Fetal Therapy Network consensus statement.

The Society for Maternal-Fetal Medicine recently released updated clinical guidelines on the ultrasound surveillance and clinical management of monochorionic twin pregnancies. The North American Fetal Therapy Network has supported but has not endorsed these guidelines. In this document, we suggest an enhanced ultrasound surveillance strategy for timely detection of twin-twin transfusion syndrome and twin anemia polycythemia sequence in monochorionic pregnancies. We provide specific recommendations that depart from the Society for Maternal-Fetal Medicine guidelines. The rationale for these recommendations includes a conceptual framework for complications of monochorionic twins, a review of Doppler studies in the diagnosis of twin-twin transfusion syndrome and a review of the pathophysiology, clinical management, and prognosis of twin anemia polycythemia sequence.