Dandy-Walker malformation as sonographic marker for fetal triploidy.

Fetal triploidy is a frequent reason for early abortion, and only few fetuses survive into the second trimester of pregnancy. Common sonographic markers for triploidy in the second trimester are severe asymmetric growth restriction (triploidy of maternal origin) and partial molar changes of the placenta (triploidy of paternal origin), together with structural fetal malformations. We report prenatal sonographic findings of thirteen triploid fetuses between 18 and 34 weeks' gestational age (eleven fetuses with 69, XXX, and two fetuses with 69, XXY). Intrauterine growth restriction (11/13 fetuses), oligohydramnios (8/13), bilateral cerebral ventriculomegaly (6/13), structural heart defects (4/13), and Dandy-Walker malformation or Dandy-Walker variant (4/13) were the most frequent findings. We conclude that the Dandy-Walker malformation and Dandy-Walker variant should be considered as additional sonographic markers for fetal triploidy.