孕妇２９岁，妊娠２８周，第二胎。第一胎为无脑畸形儿经引产证实。男女双方既往身体健康，非近亲，无遗传病史。常规超声所见：单胎头位，胎儿颅骨光环完整，脑中线居中，双顶径７．２ｃｍ，脊柱排列规整，四肢发育良好，其胎儿心室明显增大，多面观均未见室间隔回声，仅... 29-year-old pregnant, 28 weeks of pregnancy, the second child. The first child without brain abnormalities confirmed by induction of labor. Both men and women in the past healthy, non-relatives, no history of genetic disease. Conventional ultrasound see: a single fetal head, fetal skull aura intact, center line in the middle of the brain, biparietal diameter 7.2cm, regular arrangement of the spine, well-developed limbs, the fetal ventricle was significantly increased, multi-faceted no echo of interventricular septum, only...