Evaluation of prenatal central nervous system anomalies: obstetric management, fetal outcomes and chromosome abnormalities

OBJECTIVE: To study the outcomes of fetuses who were diagnosed with central nervous system (CNS) anomalies during prenatal period and to describe the obstetric management of those pregnancies. METHODS: In this retrospective study, fetuses who were detected to have central nervous system anomalies by prenatal ultrasound from January 2010 to December 2019 were recruited. Data regarding prenatal diagnosis and obstetric outcomes were retrieved from maternal and paediatric records. The prognosis of fetuses who were born alive was classified based on their neurodevelopmental outcome within two years of life. RESULTS: There were a total of 365 fetuses with CNS anomalies within the 10-year study period, with a mean gestational age of 24.65±7.37 weeks at diagnosis. Ventriculomegaly (23.36%) was the commonest CNS anomalies seen. 198 (54.20%) of these fetuses had associated extra-CNS anomalies, with cardiovascular being the most common system involved. Fetal karyotyping was performed in 111 pregnancies, with chromosomal aberrations detected in 53 (49.07%) cases and culture failure in 3 cases. Majority of the chromosomal abnormalities were Edward syndrome (trisomy 18) and Patau syndrome (trisomy 13). Fetuses with congenital CNS anomalies and abnormal chromosomal karyotyping were more likely to be diagnosed earlier by prenatal ultrasound and tend to have poorer obstetric and neurocognitive prognosis. Prenatally, 86 (23.56%) of the cases were lost to follow up and likely to deliver elsewhere. Among the 279 cases whom their pregnancy outcomes were available, 139 (49.82%) pregnancies resulted in live births, 105 (37.63%) pregnancies were electively terminated, while the remaining 35 (12.54%) pregnancies ended in spontaneous loss. The decision of termination of pregnancy largely depends on mean diagnostic gestational age, presence of chromosomal aberrations and abnormal amniotic fluid volume in those fetuses. Two years after delivery, only 75 (53.96%) children out of 139 live births were still alive, 43 (30.93%) died and 21 (15.11%) cases were lost to follow-up. 32 (23.02%) children with prenatally diagnosed CNS anomalies had normal neurodevelopmental outcome. The presence of multiple CNS anomalies and involvement of extra-CNS anomalies indicated a poorer neurodevelopmental prognosis. CONCLUSION: Less than 50% of fetuses with prenatally diagnosed CNS anomalies resulted in live births. Even if they survive till delivery, 36.45% of them passed away within 2 years and 62.79% of children who survived till 2 years old had neurodevelopmental disability.