Female, 32 years old, at 31 weeks and 5 days gestational age, presenting for further evaluation of fetal ventriculomegaly as seen on ultrasound. The lateral ventricles are enlarged, left side more so than right. The left lateral ventricle measures up to 14 mm in diameter at the level of the atrium, while the right lateral ventricle measures up to 11 mm. The left frontal horn is dilated while the right frontal horn maintains a relatively normal caliber. The third and fourth ventricles are not dilated.The cavum septum pellucidum is visualized and the corpus callosum is present. However, the degree of gyral development and sulcation is delayed for the stated gestational age of 31 weeks 5 days. In particular the sylvian fissures are underdeveloped and somewhat malformed bilaterally with poor opercularization.The cortical mantle is severely thinned bilaterally, particularly in the regions where the sylvian fissure should form. As such, the brain has assumed a pinched configuration in the transverse dimension. No evidence of any CSF clefting is seen across the cortical mantle. However, the cortical surface in the perisylvian regions shows a somewhat micronodular or cobblestoned appearance.This unusual configuration of the brain gives an impression of expanded extra-axial CSF spaces along the cerebral hemispheres, left side more than right, though the cortical veins do not appear to be displaced and there are no other findings to suggest any abnormal extra-axial collections. No evidence of acute or chronic intracranial blood product is seen. No mass lesions are appreciated. The pituitary region is unremarkable. The brainstem, cerebellar vermis and cerebellar hemispheres are normally formed.Limited views of the fetal abdomen demonstrate severe dilatation of the left renal collecting system. The right kidney is unremarkable.
Mild dilatation of the lateral ventricles is seen, left side more so than right. The third and fourth ventricles remain normal in caliber.The cortical mantle is severely thinned bilaterally with generalized under-sulcation of the brain along with delayed development of the sylvian fissure and poor opercularization.The contour of the brain appears pinched in the transverse dimension, particularly where the sylvian fissures should be forming. The cortical surface in these areas is also somewhat micronodular or cobblestoned in appearance, a finding which is suggestive of perisylvian polymicrogyria. This finding would be better assessed with postnatal MRI imaging.No evidence of any intracranial mass lesion is seen. No findings to suggest acute or chronic hemorrhage are noted. The posterior fossa structures are unremarkable.Partial visualization of the abdomen demonstrates severe dilatation of the left renal collecting system concerning for UPJ obstruction.