Arteriovenous malformations. Locations and evolution in the fetal brain

Almost all cerebral arteriovenous malformations in the fetus involve the vein of Galen, although occasionally they may involve the frontal area of the brain instead. In all reported cases arteriovenous malformations have presented some time after 30 weeks as a sonolucent oval lesion located in the midline behind the third ventricle. Previous scans have been normal. Evidence of high output failure such as cardiomegaly, enlarged neck veins, or hydrops predicts a poor outcome.