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  1. Ventriculomegaly is not a diagnosis. It is a sign. The search for all underlying causes should be immediately undertaken.

  2. Ventriculomegaly is frequently associated with a large number of intra- and extracranial chromosomal as well as nonchromosomal anomalies.

  3. For measuring the lateral ventricle it is recommended to use an axial view of the brain and to place the clipers at the level of the parieto-occipital fissure that is usually well demonstrated from 20 weeks' gestation.

  4. Congenital ventriculomegaly has a increased recurrence rate and after the birth of an affected infant a targeted neurscan is recommended in a subsequent pregnancy.

Ventriculomegaly, a term commonly employed to indicate the enlargement of the lateral cerebral ventricles, is found in ~1% of fetuses at midgestation and is the most common abnormal fetal cerebral diagnosis.

Although the enlargement of the lateral ventricles encompasses a wide spectrum of severity, at present a width of the atrium <10 mm is considered normal, 10 to 15 mm indicates mild ventriculomegaly, and >15 mm represents severe ventriculomegaly. This categorization has prognostic implications. Fetuses with normal ventricles have an exceedingly low risk of cerebral anomalies. Fetuses with mild ventriculomegaly in the majority of cases are normal at birth but have an increased risk of an abnormal outcome. Fetuses with severe ventriculomegaly have a very high probability of an abnormal outcome.

Enlargement of the cerebral lateral ventricles is not an anomaly per se. The clinical significance of this finding is that it signals to the possibility of associated anomalies of the brain or other organs. The final prognosis depends more on such anomalies than on the degree of ventricular dilation.

Fetuses with mild ventriculomegaly in particular have an increased risk of chromosomal aberrations.



Mild hydrocephaly, borderline ventriculomegaly

Definition and Diagnosis

The widely accepted definition of mild cerebral lateral ventriculomegaly is an atrial width of 10 to 15 mm on the transverse plane (Figure 4–1)1,2,3

Figure 4–1.

Mild (A) and severe (B) ventriculomegaly in midtrimester fetuses. Atrial width is 10 and 16 mm, respectively. Arrows indicate the dangling choroid plexuses.


Seen in 1% of fetuses4

Pathogenesis and Pathology

In many cases, it probably represents a normal variant. In other cases, mild enlargement of the lateral ventricles may be the only obvious epiphenomenon of heterogeneous cerebral anomalies.

Differential Diagnosis

Isolated mild ventriculomegaly should be differentiated from more complex abnormalities of the fetal brain that frequently have a different prognosis (eg, agenesis of the corpus callosum and cortical malformations). ...

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