Bilardo C
Department of Obstetrics and Gynaecology H4-205, Academic Medical Centre, Amsterdam, The Netherlands.
Early Hum Dev. 1996 Dec 30;47 Suppl:S31-3. doi: 10.1016/s0378-3782(96)01815-4.
Most fetuses with major chromosomal abnormalities have either external or internal defects that can be recognized by detailed ultrasonographic examination. These are defined as ultrasound markers for fetal chromosomal defects. In case of trisomy 13, 18, Turner's syndrome and triploidy, what we would consider as ultrasound markers are often major defects. In contrast, in Down's syndrome fetuses the structural defects are subtle and often isolated. Ultrasound screening programs for this trisomy are based on a systematic search for specific markers. Chromosomal anomalies are more common in fetuses with multisystem malformation. In fact the risk of a fetal aneuploidy increases with the number of detected defects. Other important prognostic factors are maternal age and gestational age. For every single structural abnormality it is possible to estimate the specific risk of this being a phenotypic expression of a chromosomal defect according to whether it is isolated or associated to more structural defects. This risk will also be influenced by the maternal age and the gestational age.
大多数患有主要染色体异常的胎儿都有外部或内部缺陷，这些缺陷可通过详细的超声检查识别出来。这些被定义为胎儿染色体缺陷的超声标志物。在13三体、18三体、特纳综合征和三倍体的情况下，我们认为的超声标志物通常是主要缺陷。相比之下，唐氏综合征胎儿的结构缺陷很细微，且往往是孤立的。针对这种三体综合征的超声筛查程序基于对特定标志物的系统搜索。染色体异常在患有多系统畸形的胎儿中更为常见。事实上，胎儿非整倍体的风险会随着检测到的缺陷数量增加而升高。其他重要的预后因素是母亲年龄和孕周。对于每一个单一的结构异常，根据其是孤立的还是与更多结构缺陷相关联，可以估计其作为染色体缺陷表型表达的具体风险。这种风险也会受到母亲年龄和孕周的影响。
