Fetal Cerebral Ventricular Pointing as a Marker of Spina Bifida

Abstract

Occipital cerebral ventricular pointing is a promising intracranial marker for spina bifida. We sought to determine (1) the incidence of pointing in fetuses with and without spina bifida and (2) inter-observer and intraobserver agreement for visualizing pointing. Second-trimester transverse axial images of the lateral cerebral ventricles from an equal number of affected and unaffected fetuses were independently reviewed in a blinded fashion by 2 examiners. Sixty-two fetuses (31 with isolated spina bifida and 31 without) had sonographic examinations at 19.2+/-1.3 weeks (mean+/-SD). Pointing was present in 77.3% of fetuses with spina bifida and 15% of those without by the first examiner and in 78.3% of fetuses with spina bifida and 10% of those without by the second examiner. Interobserver and intraobserver agreement were substantial (kappa=0.69 and 0.78, respectively). Ventricular pointing is a highly agreed-on finding that is substantially associated with but not pathognomonic for fetal spina bifida.