Prenatal sonography in hydranencephaly: findings during the early stages of disease.

The purpose of this report is to describe the prenatal sonographic findings in fetuses with hydranencephaly diagnosed during the early stages of disease. Four cases with characteristics of hydranencephaly were retrospectively identified from 2 Latin American fetal medicine referral centers. Information on maternal demographics, sonographic findings, antenatal courses, and pregnancy outcomes was retrieved from the ultrasound reports and medical records. Cases were diagnosed between 21 and 23 weeks' gestation. The sonographic findings were similar in all cases and included absent cerebral hemispheres, which were replaced by homogeneous echogenic material filling the supratentorial space, and preservation of the thalami, brain stem, and cerebellum. The head circumference measurement was within the normal range, but the transverse cerebellar diameter was below the fifth percentile in 3 of the 4 cases. A follow-up scan in 1 of these cases demonstrated the classic anechoic fluid-filled appearance of hydranencephaly 2 weeks after diagnosis. Confirmation of the diagnosis was available in 2 cases, by postmortem examination in 1 and by fetal magnetic resonance imaging in the other. No further investigations were performed in the 2 women who opted for termination of pregnancy. In conclusion, during the early stages of disease, hydranencephaly is characterized by the presence of a large intracranial saclike structure containing homogeneous echogenic material, representing blood and necrotic debris secondary to massive liquefaction of the developing cerebral hemispheres.