I went straight home and googled ‘ventriculomegaly’. Here’s what it said on Wikipedia:
``Ventriculomegaly is a brain condition that occurs when the lateral ventricles become dilated. The most common definition uses a width of the atrium of the lateral ventricle of greater than 10 mm. This occurs in around 1% of pregnancies. When this measurement is between 10 and 15 mm, the ventriculomegaly may be described as mild to moderate. When the measurement is greater than 15mm, the ventriculomegaly may be classified as more severe. Enlargement of the ventricles may occur for a number of reasons, such as loss of brain volume (perhaps due to infection or infarction), or impaired outflow or absorption of cerebrospinal fluid from the ventricles. Often, however, there is no identifiable cause.
Associations
Ventriculomegaly is also known to be associated with other malformations such as agenesis of the corpus callosum, spina bifida, and heart defects. Fetuses with both isolated ventriculomegaly and with other anomalies have an increased risk of having a chromosomal abnormality, including that of Down Syndrome. Many conditions associated with ventriculomegaly can be defined prior to birth, but the possibility remains of other anomalies (either structural, chromosomal or genetic) only being identified later in pregnancy or after birth. Ventriculomegaly associated with abnormal findings and other structural malformations, often has an adverse prognosis, which ranges from disability (often mild) to death. However, in cases of mild isolated ventriculomegaly, there is around a 90% chance of a normal outcome.’’
I read this, and the thing that leapt out at me was that ventriculomegaly is apparently associated with agenesis of the corpus callosum, what our first baby had. But this baby has his corpus callosum, I had asked the ultrasound technician specifically. But what is going on, surely this cannot be a coincidence??