Kleeblattschadel anomaly. In utero sonographic appearance.

Four cases of Kleeblattschadel demonstrated on prenatal ultrasound examinations are reported. Five additional cases from the literature are reviewed. Sonographic features include enlarged trilobed skull, hydrocephalus, polyhydramnios, and frequent association with thanatophoric dwarfism. The most common error in diagnosis was misinterpretation of this skull anomaly as encephalocele.