An incidental ultrasound diagnosis of a vein of Galen malformation at 38 weeks and 5 days' gestation
Jennifer Johnson, Mid Yorkshire Hospitals NHS Trust
Background
A 26-year-old primigravida patient was referred for an ultrasound scan at 38 weeks and 5 days' gestation due to a history of reduced fetal movements. Her dating and anatomy scans had been unremarkable and a growth scan performed at 31 + 5 for tailing growth had not shown any abnormalities.
Case summary
Ultrasound examination revealed that the fetus was in a breech position and an elongated midline cystic structure was seen within the fetal head. This was found to be highly vascular on colour Doppler interrogation, with mixed arterial and venous high-velocity flow noted. A vein of Galen malformation was suspected. Following discussion with the local tertiary referral centre, the patient was transferred for repeat scan with fetal medicine. They agreed with our findings and the patient was transferred out of area due to the need for immediate transfer to a national centre of expertise following birth. A live female was delivered by caesarean section at 39 weeks and 2 days' gestation. She clinically worsened during the first week of life and an embolization procedure was performed on day 25. The post-operative period was complicated by a thalamic bleed and intraventricular haemorrhage requiring insertion of a drain; however, the patient is now doing well albeit with some right-sided hemiparesis.
Conclusion
A vein of Galen malformation is a rare form of a cerebral arteriovenous malformation and is a defect which occurs early in embryonic development. It is not usually sonographically apparent until the third trimester. Antenatally, they present as a midline cystic structure with arteriovenous flow on colour Doppler as in this case. Cardiomegaly, fetal hydrops and ventriculomegaly can also occur.