Findings are in keeping with Dandy walker malformation with dysgenesis of corpus callosum. 

Dandy-Walker malformation is the most common posterior fossa malformation, characterized by the triad of: enlarged posterior fossa , hypoplasia of the vermis and cephalad rotation of the vermian remnant and cystic dilatation of the 4th ventricle posteriorly. 

Dandy-Walker continuum, also referred to as Dandy-Walker spectrum corresponds to a group of congenital anomalies believed to represent a continuum spectrum of posterior fossa malformations, characterized by inferior vermian hypoplasia and incomplete formation of the fourth ventricle which communicates with a prominent posterior fossa CSF space. 

The tegmentovermian angle is an important measurable parameter in the assessment of posterior fossa abnormalities in the fetus. The angle is constructed on midsagittal images of the fetal brain, ideally on MRI. In case of Dandy- Walker malformation it is > 45⁰ .