19-week male fetus with myelomeningocele

Images from longitudinal ultrasound (A) and sagittal SSFSE T2-weighted MRI (B) show an overlying thin-walled sac (arrows). The portion of the brain seen on MRI shows a typical Chiari II malformation (arrowhead). Transverse ultrasound image of the fetal brain (C) shows typical inward bowing of the frontal bones (lemon sign, dashed arrows) and crowding of the posterior fossa structures (banana sign, curved arrow) seen in the Chiari II malformation.