EP05.24: Incidence of structural and chromosomal abnormalities in fetus with lateral ventricular atrium width between 9 and 9.9mm

To evaluate the incidence of structural and chromosomal abnormalities in fetuses with lateral ventricular atrium width between 9-9.9mm. Retrospective study including fetuses with at least one lateral ventricular atrium width between 9-9.9mm referred to our neurosonography unit from May 2014-October 2023. Collected data included maternal characteristics, ventricular width, laterality, associated anomalies including intra- or extracentral nervous system (CNS), genetic and infection results and pregnancy outcomes. We included 159 fetuses with a mean ventricular width of 9.4 ± 0.3 at diagnosis. Mean gestational age at diagnosis was 27.0 weeks (20.0-37.6) and 8% (n = 13) of cases progressed to ventriculomegaly while 44% (n = 70) showed regression. Associated structural anomalies were identified in 62 fetuses (39%) of which 48 (77.4%) had another intra-CNS anomaly and 29 (46.8%) had an extra-CNS. 59% of the patients accepted amniocentesis, a genetic anomaly was found in 7 cases (7.5%), 6 of them had associated anomalies. Genetic alterations were diagnosed in 5 newborns, leading a total incidence of genetic anomalies of 7.5%(12/159). Non-isolated cases showed an increased prevalence of genetic anomalies compared to the isolated (17.7% vs 1%,p = 0.001). No significant differences in genetic abnormality rate was observed between unilateral and bilateral cases (5.9% vs 9.5%,p = 0.69), being most frequent in those that progressed vs those that regressed (7.7% vs 1.4%). CMV infection in amniotic fluid was identified in one patient (1.1%). Pregnancy was terminated in 9 cases (6.1%) due to the severity of associated anomalies (n = 6) or chromosomal abnormalities (n = 3). Fetal lateral ventricular atrium between 9-9.9mm is associated with a significant proportion of structural anomalies, being genetic anomalies more frequent in non-isolated cases. Based on these findings, we suggest to perform a neurosonography and considering genetic study, especially in those cases with atrium between 9 and 9.9mm and associated anomalies.