Prevalence:

• 1 in 200,000 births.

Ultrasound diagnosis:

• Avascular, supratentorial, hyperechogenic mass in the posterior fossa above the cerebellum, surrounded by a triangular sonolucent area (the dilated venous sinus).

Associated abnormalities:

• The incidence of chromosomal abnormalities and genetic syndromes is not increased.

Investigations:

• Detailed ultrasound examination, including neurosonography.
• Fetal brain MRI is necessary to confirm the diagnosis and describe its location and size.

Follow up:

• Ultrasound scans every 4 weeks to monitor the evolution of the lesion.
• Repeat MRI after 6-8 weeks to exclude infarction and hemorrhage of the cerebral parenchyma.

Delivery:

• Standard obstetric care and delivery.

Prognosis:

• Normal head size with decreasing thrombus size indicate a favourable prognosis. Postnatally, management is usually non-interventional.

Recurrence:

• No increased risk of recurrence.