Monozygotic twin pregnancies present unique challenges in prenatal ultrasound, requiring accurate diagnosis and regular monitoring. Among these, monochorionic diamniotic (MCDA) twins face a distinct set of complications related to their zygosity and development, including twin-to-twin transfusion syndrome, twin reversed arterial perfusion, and selective growth restriction. Ultrasound assessment plays a crucial role in diagnosing these conditions, providing essential guidance for treatment and delivery planning. This workshop will emphasize the importance of recognizing sonographic features specific to MCDA twins from the first to the third trimester, and the correct methods for identifying and measuring key parameters, such as amniotic fluid levels and chorionic membranes.