The midsagittal view of the fetal brain: a useful landmark in recognizing the cause of fetal cerebral ventriculomegaly

To evaluate the positive predictive value of the midsagittal view of the fetal brain in recognizing the cause of ventriculomegaly diagnosed with traditional axial scan. METHODS: Fifty-eight pregnant women, referred to our Center following a generic diagnosis of ventriculomegaly have been evaluated: 38 had marked and 20 had borderline ventriculomegaly. The fetal brain was scanned by the midsagittal view using a transabdominal probe in fetuses in breech presentation or transverse lie and a transvaginal probe in fetuses in cephalic presentation. The possible cause of ventriculomegaly was postulated by combining the findings of the corpus callosum/cavum septi pellucidi complex with those of the posterior fossa. The prenatal diagnoses were compared with the anatomical specimens of aborted fetuses or with postnatal neuroimaging. RESULTS: The prenatal diagnoses were confirmed in 54/58 cases (PPV 93.1%). In the marked ventriculomegaly group, one case of partial agenesis of the corpus callosum was mistaken for a complete agenesis. In the group of borderline ventriculomegaly, two cases of partial agenesis of the corpus callosum were confused with a complete agenesis, while one case of suspected isolated ventriculomegaly was diagnosed after birth as partial agenesis of the corpus callosum. CONCLUSIONS: The sagittal scan of the fetal brain is a useful source of information and allows the contemporary view of both corpus callosum and posterior fossa, where various typical sonographic findings are present in ventriculomegaly.