Surveillance of Monochorionic Twins for Detection of Twin-Twin Transfusion Syndrome and Twin Anemia Polycythemia Sequence: A North American Fetal Therapy Network (NAFTNet) Consensus Statement: NAFTNet consensus on monochorionic pregnancy surveillance.

The Society for Maternal Fetal Medicine (SMFM) recently released updated clinical guidelines on the ultrasound surveillance and clinical management of monochorionic (MC) twin pregnancies. The North American Fetal Therapy Network (NAFTNet) 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 (TTTS) and twin anemia polycythemia sequence (TAPS) in MC pregnancies. We provide specific recommendations that depart from the SMFM guidelines. The rationale for these recommendations includes a conceptual framework for complications of MC twins, a review of Doppler studies in the diagnosis of TTTS and a review of the pathophysiology, clinical management and prognosis of TAPS.