Prenatal ultrasonography in the diagnosis of vein of Galen aneurysm.

Vein of Galen aneurysm is a rare congenital anomaly, originated from a defect in fusion of internal cerebral veins. Due to low resistance, it produces high debit cardiac insufficiency. It constitutes 1% of all intracranial vascular malformations. Prognosis depends on patient's age when the manifestation occurs and aneurysm size. The two reported cases are about fetal prenatal diagnosis of vein of Galen aneurysm, confirmed by ultrasonography, which evolved for caesarian delivery at term gestation. Magnetic resonance was carried out after birth, confirming prenatal diagnosis. The first patient had spontaneous thrombosis of the aneurysm while the second was submitted to embolization. Both of them had hospital discharge with ambulatory accompaniment. The prenatal ultrasonography diagnosis is fundamental to determine aneurysm size, defining the best treatment, when this procedure is indicated, and the more adequate obstetric and perinatal assistance.