Ultrasound imaging of the cranium and spine.

A general description and discussion of the normal head and spine, and major fetal anomalies has been presented. It is important to remember that there can be wide variability in the structural findings noted in the fetus with ventricular dilatation or abnormal cerebellar development. If an abnormality of the fetal head and spine is seen, it is important to carefully assess other areas of fetal anatomy because of the increased likelihood of coexisting anomalies. Because of the increased incidence of chromosomal abnormalities, evaluation by percutaneous umbilical blood sampling, amniocentesis or placental biopsy is recommended for all structural abnormalities of the fetal head and spine. The best clinical approach for the ultrasonologist is to accurately describe and quantify the abnormalities for geneticist, pediatrician and or neurosurgeon to discuss the prognosis. Accurate evaluation of the type, location and extent of a neural tube defect is important to enable the family to understand possible outcomes of the pregnancy.