Ventricular septal defect with overriding aorta in trisomy-18.

In a child with trisomy-18 prenatal echocardiography demonstrated the presence of a ventricular septal defect with overriding aorta. In a previous anatomical study of 18 hearts with this malformation we found a 50% concurrence rate with trisomy-18. In case of prenatal echocardiographic detection of a ventricular septal defect with overriding aorta, we advise thorough ultrasound examination for additional malformations as seen in trisomy-18; subsequently this procedure should be completed by cytogenetic analysis of amniotic cells.