Sonographic markers of exencephaly below 10 weeks' gestation.

We report two cases of exencephaly diagnosed by transvaginal ultrasonography at 8 weeks 4 days and at 9 weeks 3 days of gestation. Both cases presented an irregular cephalic pole, and, in the case seen at 8 weeks 4 days, brain vesicles were also absent, whereas in the case seen at 9 weeks 3 days, the midline echo was indistinguishable with disorganized choroid plexuses. In both cases, anencephaly was evident at 11 and 12 weeks' gestation and the postmortem confirmed the diagnosis.