TY - CHAP M1 - Book, Section TI - Malformations in Twins A1 - Bianchi, Diana W. A1 - Crombleholme, Timothy M. A1 - D'Alton, Mary E. A1 - Malone, Fergal D. Y1 - 2015 N1 - T2 - Fetology: Diagnosis and Management of the Fetal Patient, 2e AB - Key PointsCongenital malformations occur more commonly in twins as compared with singleton gestations and are an important contributor to the increased perinatal mortality associated with multiple gestations.The incidence of congenital anomalies is thought to be more common in monozygotic compared with dizygotic twin pregnancies.Antenatal ultrasound examination is used to detect malformations in twin pregnancies.The antenatal natural history will depend on the malformation diagnosed, whether or not it is discordant, and thechorionicity of the pregnancy.The management will be influenced by the type of abnormality, whether or not it is concordant, the gestational age when diagnosed, and chorionicity.Counseling of parents depends on the type of abnormality and the prognosis for the anomalous twin as well as on the likely outcome for the normal co-twin.Three management options are available in this situation: expectant management, selective termination of the anomalous fetus, and termination of the entire pregnancy.Expectant management of a twin pregnancy discordant for an abnormality is associated with an increased risk for preterm delivery.The method chosen for selective termination will depend on chorionicity. Intracardiac injection of potassium chloride is safe in dichorionic twins, while cord occlusive techniques are necessary for monochorionic pregnancies.Treatment of neonatal twins with malformations will depend on the particular malformation.The recurrence risk for malformations seen in twin pregnancies will depend on the specific abnormality. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/04/20 UR - obgyn.mhmedical.com/content.aspx?aid=1106401184 ER -