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This condition is an enlargement of the lateral ventricles (the fluid-filled spaces normally found in each side of the brain).

Ventriculomegaly is found via ultrasound in approximately one to two per 1,000 babies.

A normal lateral ventricle is usually less than 10 millimeters wide until 35 weeks of pregnancy.

  • Mild ventriculomegaly is generally in the range of 10-15 mm.
  • Severe ventriculomegaly (hydrocephalus) is defined as a width greater than 15 mm.

Most babies with mild ventriculomegaly are normal. However, it can sometimes indicate a chromosome problem, bleeding, infection, or a genetic syndrome.

Causes of ventriculomegaly

  • Lateral ventricles are normally filled with cerebrospinal fluid (CSF). If the amount of fluid increases enough, the ventricles will also grow. CSF may increase because it isn't circulating well, too much CSF is being produced, or there is a problem with the brain.
  • If we can determine the cause, we can more effectively determine its effects on the baby.
  • Some cases of ventriculomegaly improve, some stay the same, and some get worse. Because it is difficult to predict the outcome, it is a good idea to have repeat ultrasounds.

Further testing

  • You can have a more detailed ultrasound to look for other abnormalities.
  • The maternal serum screening can assess your risk of having a baby with Down syndrome, through 21 weeks' gestation.
  • A blood test may be suggested to look for some infections or bleeding conditions.
  • An amniocentesis can diagnose a chromosome abnormality or infection. Amniocentesis involves obtaining a sample of the fluid surrounding the baby, which is then used to study the fetal chromosomes. There is a small risk of miscarriage from amniocentesis.
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