Fig. 1

(a) The ultrasound examination of the first case with a hyperechogenic of fetal aortic valve (white arrow). b The ultrasound images of the second case in oblique view through oral fissure, showing break in echo of palatine bone horizontal plate(white arrow). c The ultrasound images of the second case showed a low-lying conus medullaris, the CM located at the L4 level. d, k, l The ultrasound view showed left mild ventriculomegaly in case 3(d), and bilateral mild ventriculomegaly in case 6 and 7(k,l). e, f The ultrasonic examination of the third case showed severe hydronephrosis of the left kidney with dilatation of the left ureter. g, h The ultrasonic examination of the fourth case showed an absent upper cranial vault and no cerebral tissue above the level of the orbits in the coronal view (g) and the coronal view (h). i, j The ultrasound images of the sixth and seventh cases showed the inner diameter of the ascending aorta was widened in the left ventricular outflow tract view and the long axis of the aortic arch view