Prevalence:

• 1 in 50,000 births.

Ultrasound diagnosis:

• The cranial cavity is fluid filled and there is no remaining cortex. The falx cerebri and posterior fossa are normal.

Associated abnormalities:

• The incidence of chromosomal abnormalities and genetic syndromes is not increased.
• The causes are vascular occlusion in the internal carotid artery, fetal infection or prolonged ventriculomegaly.

Investigations:

• Detailed ultrasound examination including neurosonography.
• TORCH test for fetal infections.

Follow up:

• If pregnancy continues, follow-up should be standard.

Delivery:

• Standard obstetric care and delivery.
• If the head is circumference is >40cm, cephalocentesis may be needed before vaginal delivery.

Prognosis:

• Death in early infancy.

Recurrence:

• No increased risk of recurrence.