First-trimester transvaginal ultrasonographic diagnosis of Dandy-Walker malformation

We present transvaginal ultrasonographic findings of a fetus with Dandy-Wal ker malformation and associated massive obstructive hydrocephalus at 13 wee ks' gestation. First-trimester ultrasonographic diagnosis of Dandy Walker m alformation is uncommon with only two such occurrences having been reported previously. These cases and recent reports of single gene transmission of this condition in some families emphasize the importance of first-trimester transvaginal ultrasound assessment especially in women with previously aff ected fetuses.