Twenty-six-week fetus. SSFSE T2WIs in different planes; coronal, axial, and sagittal images a, b show asymmetric severe dilatation of lateral ventricle (right reaching 21 mm while the left reaching 15 mm in atrial width), secondary obliteration of the extra-axial spaces and thinning out of the cerebral parenchyma. There is a focal cortical destruction in both frontal and the left occipital lobes (spontaneous ventriculostomy). c The aqueduct of Sylvius cannot be visualized. Incomplete separation of both lateral ventricles because of interruption of septum pellucidum secondary to sever ventriculomegaly that could resemble mono-ventricle of holoprosencephaly; however, normal anterior and posterior cleavage of the cerebrum rules out the diagnosis of holoprosencephaly. MRI diagnosis: Severe supratentorial ventriculomegaly secondary to aqueduct stenosis. Recommendation: Termination of pregnancy.