Diagnostic approach to fetal ventriculomegaly

Ventriculomegaly (VM) is defined as an enlargement of the lateral ventricles of the developing fetal brain. The diagnosis is easily made by measuring the lateral ventricle width at the level of the atrium, which is normally <10 mm. VM is defined as mild when the atrial width is 10-12 mm, moderate 12-15 mm, severe >15 mm. VM is a non-specific sonographic sign which is common to different pathological entities and genetic conditions. When no associated anomaly can be found VM is defined as isolated. Since the prognosis of fetal VM mainly depends on the presence of associated anomalies, a careful diagnostic approach is necessary to rule out CNS and extra- CNS fetal anomalies. Magnetic Resonance Imaging can be a useful diagnostic tool complementary to ultrasound in order to recognize subtle brain anomalies, particularly cortical disorders. In this review the diagnostic approach to fetal VM will be discussed starting from ultrasound screening, moving to neurosonographic and MRI examination and genetic evaluation, in order to recognize the cause of VM and offer the appropriate counselling to the parents.