Differential diagnosis and outcome of fetal intracranial hypoechoic lesions: report of 21 cases.

Our objective was to evaluate the diagnostic and prognostic value of sonography hypoechoic lesions. A retrospective study revealed revealed a total of 21 cases diagnosed over a period of 10 years. Most of the diagnosis were made in the third trimester. The presence fluid-filled lesions within the brain matter always predicted porencephaly and a poor outcome. In most of these cases (nine out of ten), the lesions were seen to communicate with the cavity of the lateral ventricles. Among the 11 cases of hypoechoic lesions that were external to the brain matter, Doppler ultrasound was always able to distinguish between arachnoid cysts (seven cases) and vein of Galen aneurysms (four cases). Arachnoid cysts were associated with a good outcome in four out of the five pregnancies that delivered at term. Three of the four cases of vein of Galen aneurysm were associated with distortion of the cerebral architecture and/or hydrops: one pregnancy was terminated and two resulted in early postnatal death. One pregnancy with vein of Galen aneurysm and normal cerebral structures, without signs of hydrops, had a good outcome. It is concluded that current antenatal ultrasound has the capability of accurate differentiation between different clinical entities resulting in fetal intracranial hypoechoic lesions, and that the sonographic findings have practical clinical implications.