CNS anomalies are some of the most common and clinically important congenital malformations encountered in utero. Improved detection of CNS anomalies requires a systematic survey of the cranium and spine as a part of all obstetric sonograms performed after the first trimester. Recognition of characteristic cranial findings associated with spina bifida can dramatically improve detection of small spinal defects before the time of fetal viability, even when the sonogram is performed for low-risk indications. Patients suspected to be carrying a fetus that has a cranial or spinal anomaly should ideally be referred to a tertiary center for confirmation of the defect, evaluation of possible additional anomalies, and for patient management and counseling.