Sonographic anatomy of the fetal cerebral ventricles, with reference to the early diagnosis of hydrocephaly.

Real time ultrasound was used to evaluate the anatomy of the fetal brain at different gestational ages. Anatomical correlation with the gross brain was utilized for more accurate identification of the neuroanatomical structures. The normal growth of the ventricular system was studied. Transaxial measurements of the anterior horn (AH) and maximum ventricular length (MVL) and width (MVW) were made, and enlarged as pregnancy progressed. The ratios of MVW/MVL, MVL/BPD, and MVW/BPD provide guides to the early diagnosis of hydrocephalus and intracranial abnormalities. Specific measurements of the cerebral ventricles at various gestational ages may be made accurately by utilizing the anatomical landmarks. The anterior horn and midbrain measurements are of little value in the early diagnosis of hydrocephaly. Maximum ventricular length and width are the most useful determinants of hydrocephaly, even as early as 20 weeks. A set of discordant twins in which twin B was found to be hydrocephalic by these studies in the twentieth week is presented with serial measurements for both twins. Multiple measurements of the cerebral ventricular system in utero permit early and precise diagnosis of fetal hydrocephaly.