Management and Implications of Enlarged Cisterna Magna on Fetal Ultrasound

Evaluation and Management

A detailed obstetrical ultrasound examination should be performed to evaluate for associated anomalies, including careful assessment of cerebellar size and morphology, other brain structures, and a comprehensive fetal anatomic survey, as recommended by the American College of Obstetricians and Gynecologists 1
For isolated enlarged cisterna magna with no other abnormalities, routine aneuploidy screening, such as cell-free DNA or serum screening, is appropriate, according to the American College of Radiology 3
If other abnormalities are present, consider diagnostic testing with chromosomal microarray analysis, as recommended by the American College of Obstetricians and Gynecologists and the American College of Radiology 1, 3
Pediatric providers should be informed of the antenatal finding at the time of delivery for appropriate postnatal follow-up, as suggested by the American Academy of Pediatrics 2

When isolated, a follow-up ultrasound in the third trimester is recommended to reassess the finding and evaluate fetal growth, as recommended by the American College of Obstetricians and Gynecologists 2