Implication of New High Resolution Ultrasonographic Modalities for Diagnosis of Fetal Nervous System Anomalies

The fetal CNS screening examination during the mid-trimester scan in low-risk pregnancies should include evaluation of the fetal head and spine, using transabdominal sonography. Evaluation of two axial planes allows visualization of the relevant cerebral structures to assess the anatomic integrity of the fetal brain.These planes are commonly referred to as the transventricular and transcerebellar planes. A third plane, the so-called transthalamic plane, is frequently added, mostly for the purpose of biometry. Structures that should be noted in the routine examination include the lateral ventricles, the cerebellum, the cisterna magna, and the cavum septi pellucidi (CSP). Head shape and brain texture should also be noted on these views.