OP12.01: Global lateral ventricles biometry in normal fetuses compared to fetuses at risk or with known ventriculomegaly

Ventricular atrial width (AW) measurement is an integral part of the evaluation of the fetal brain. Little is known about how other portions of the ventricle vary in size in normal and abnormal fetuses. Moreover, AW is not evaluated postnatally; measurements of other segments of the ventricles are used in the newborns, making it difficult to compare fetal and neonatal ventricular measurements. The aim of this study was to assess in the fetus the ventricular measurements usually performed in neonates and evaluate how these indices might be useful in fetuses at risk or with known ventriculomegaly. A total of 625 normal fetuses between 19 and 32 weeks were studied prospectively in two referral centres. The following measurements were taken: AW (axial plane), anterior horn width (AHW) (coronal plane), ventricular height (VH) and thalamo-occipital distance (TOD) (parasagittal plane). Additionally, 22 fetuses at risk (AW 9.1-9.9 mm) and 23 fetuses with ventriculomegaly (AW 10.0-19.6 mm) were included. An extended ventricular biometry was feasible and reproducible. The mean + 3 SD of the AW, AHW, VH and TOD was 9.9, 5.0, 4.6 and 27.6 mm, respectively. Measurements of the different segments of the lateral ventricles were all correlated. In fetuses at risk or with ventriculomegaly, AW and AHW were the two portions more dilated. In cases of atrium 9.1-9.9 mm, 3/4 who had increased AHW progressed to ventriculomegaly. Later regression of the ventriculomegaly was observed in 5/5 fetuses who had a normal AHW. AW is a good method of screening for ventriculomegaly prenatally. Our preliminary results show that measurement of other portions of the ventricle (specially AHW) might help to identify progression to ventriculomegaly in fetuses at risk, or potential regression in fetuses with known ventriculomegaly. It also allows comparison between fetal and neonatal measurements. Larger studies are needed to corroborate our findings.