Erroneous sonographic identification of fetal lateral ventricles: relationship to the echogenic periventricular "blush".

We show, through correlation of fetal, neonatal, and necropsy brain sonography, that the three-parallel-echogenic-line configuration classically thought to represent fetal lateral ventricular margins on high axial images are actually extraventricular, lying within cerebral white matter. Accurate sonographic identification of fetal hydrocephalus is essential for appropriate patient management. Both qualitative and quantitative methods of determining ventriculomegaly have been described. The latter require identification of lateral ventricular walls for subsequent ventricular mensuration and comparison with hemispheric width. The parallel-line configuration, thought to represent ventricular margins, has been used for such measurements. We have--through careful fetal, neonatal, and necropsy specimen scanning in several planes--determined that the presumed ventricular wall echoes are actually extraventricular, arising from fibers within the cerebral white matter aligned perpendicular to the sonographic beam. This is identical to the etiology of the normal echogenic periventricular "blush" described in the neonate. Since these parallel echogenic lines do not represent actual ventricular margins, they should not be relied upon for the diagnosis of ventriculomegaly.