It can be done before birth via chorionic-villus sampling or amniocentesis.

它可以在出过绒膜-绒或羊膜穿刺术完成。

This can also be done prenatally by testing fetal DNA obtained through either chorionic villus sampling or amniocentesis.

可以在产过检测胎儿DNA完成，如绒膜绒或羊膜穿刺术。

A karyotype can be done before birth with an amniocentesis or at any time after birth with the blood test.

核型分析在出就可以用羊膜穿刺术或在出后采血。

In more serious cases, amniocentesis, where a sample is taken directly from the amniotic sac surrounding the fetus, can be performed.

在严重的情况下，需行羊膜穿刺术，即直接从胎儿周围的羊膜囊穿刺检查。