产前发现的绒毛或羊水细胞镶嵌体对准确预测胎儿的核型和预后颇为困难,因为异常的细胞可能来自胎儿自身,也可能来自胚外组织。异常细胞只局限于胎盘组织的绒毛细胞镶嵌体是较为常见的现象,胎儿核型正常。羊水细胞镶嵌体的异常细胞来源于胚外组织的情况也有报道,因此即使是Ⅲ级水平的羊水镶嵌体,也不等同于胎儿核型异常。 Prenatal discovery of villi or amniotic fluid cell mosaicism accurately predicts the fetal karyotype and prognosis is difficult, because abnormal cells may come from the fetus itself, but also may come from the extra-embryonic tissue. Abnormal cells confined to the placenta villus cell mosaic is a more common phenomenon, the normal fetal karyotype. Abnormal cells in amniotic fluid cell mosaicism are also reported from the extraembryonic tissue. Therefore, even amniotic fluid inlays of grade III level are not equivalent to fetal karyotypic abnormalities.