A.脊柱中線缺損
	B.胎兒軀干縱切圖上,脊柱結(jié)構(gòu)中斷
	C.胎兒軀干橫切圖上呈"U"字形
	D.胎兒小腦可顯示香蕉征
	E.脊管呈封閉的環(huán)狀強(qiáng)回聲
 
                            
	A.2~5.6mm
	B.10.6~11.6mm
	C.12~13mm
	D.13~14mm
	E.14~16mm
	A.小于2周
	B.5~8周
	C.15~20周
	D.20~22周
	E.22~24周
