DANDY-WALKER MALFORMATION DIAGNOSED BEFORE 21 WEEKS OF GESTATION - ASSOCIATED MALFORMATIONS AND CHROMOSOMAL-ABNORMALITIES

This study examined rates of concomitant structural and chromosomal ab normalities in 14 fetuses with a diagnosis of Dandy-Walker malformatio n or Dandy-Walker variant before 21 weeks' gestational age, compared t o 14 fetuses with a diagnosis of Dandy-Walker malformation or variant between 21 weeks' gestation and delivery. A total of 24 fetuses had Da ndy-Walker malformation and four had Dandy-Walker variant. Eight of th e fetuses with the malformation had ventriculomegaly: one of the fetus es with early diagnosis and seven with later diagnosis (p=0.027). None of the fetuses with Dandy-Walker variant had ventriculomegaly. The ov erall prevalence of concomitant structural abnormalities was 13/28; 8/ 14 for fetuses with early prenatal diagnosis and 5/14 for fetuses with late prenatal diagnosis of the malformation or the variant. Chromosom al abnormality rates were significantly higher among fetuses with earl y prenatal diagnosis (7/14) than among those with later prenatal diagn osis (1/14; p=0.032). Abnormal Karyotypes were mole prevalent among fe tuses without ventriculomegaly (7/20), compared to fetuses with ventri culomegaly (1/8). We conclude that fetuses with an antenatal diagnosis of Dandy-Walker malformation or Dandy-Walker variant before 21 weeks' gestational age have worse prognosis than fetuses with a later prenat al diagnosis of the same defect.