Clinical Considerations of Major Congenital Anomalies in Twin Pregnancy

Objective: To present 43 cases of major congenital anomalies in twin pregnancies. Methods: Among 899 twins from June 1994 to January 2007, 43 twin sets with major congenital anomalies, managed and delivered in our center, were retrospectively reviewed. Classifications of anomalies, clinical characteristics, chorionicity, and anomalies unique to monochorionic twin were analyzed. Results: The rate of major congenital anomalies was 4.7% (43/899). The mean gestational age at initial diagnosis and delivery were 23 and 29 weeks respectively. Preterm deliveries less than 37 gestational weeks accounted for 83%. In aspect of chorionicity, 51% was monochorionic and the other half was dichorionic. The most common anomalies in organ system was central nervous system (18.6%) followed by genitourinary (16.2%), multiple (16.3%), face and neck (11.6%) anomalies and etc. There were 5 cases of 2 unique anomalies confined to monochorionic twin: conjoined and acardiac twin. Among obstetrical complications, high incidence of preterm deliveries (83%) was observed and the rate of hydramnios and oligohydramnios were 16.3% and 11.6% respectively followed by discordant fetal growth and preeclampsia (6.9%). Conclusion: The overall incidence of major congenital anomalies in twin pregnancy was 4.7%. Our analysis gives useful information for better understanding of anomalies in twin pregnancies. The Korean Journal of Ultrasound in Obstetrics and Gynecology 10(1):19-26, 2008