label: Enlarged fetal cisterna magna
label_lc: enlarged fetal cisterna magna
description: "The cisterna magna is measured on a transaxial view of the fetal head angled 15 degrees caudal to the canthomeatal line. The anterior/posterior diameter is taken between the inferior/posterior surface of the vermis of the cerebellum to the inner surface of the cranium. An enlarged cisternal magna is defined by an anterior/posterior diameter of 10 mm or more (PMID:16100637)."