Dizygotic Twin Pregnancy Discordant for Sirenomelia

win pregnancies pose a real challenge to caregivers for several reasons.Maternal and perinatal complications are higher in twins than in singletonpregnancies. Preterm deliveries, a higher rate of structural malformations,and perinatal mortality place twin pregnancies at greater risk. Likewise, theanatomic survey in twin pregnancies is more difficult, and rare malformations mightbe masked by more common conditions. Amniotic fluid volume and fetal growth dis-cordancy may appear either in twin-twin transfusion syndrome (TTTS) or in placen-tal, structural, and genetic disorders of one of the twins. Twin-twin transfusionsyndrome is a complication of monochorionic multiple pregnancies; therefore, adetermination of chorionicity and a thorough scanning for fetal anomalies are nec-essary for proper diagnosis and optimal pregnancy management.We report a case of dizygotic twin pregnancy discordant for sirenomelia referred assuspected TTTS. The diagnostic and management aspects of sirenomelia in twin preg-nancies are discussed.