Benacerraf Beryl R
Harvard Medical School, Boston, MA, USA.
Semin Perinatol. 2005 Dec;29(6):386-94. doi: 10.1053/j.semperi.2005.12.003.
The Genetic Sonogram is an ultrasound examination done on second trimester fetuses that not only evaluates the fetus for structural malformations, but also searches for the sonographic markers of fetal Down syndrome. The main markers that comprise the genetic sonogram include the nuchal fold, short femur and humerus, pyelectasis, hyperechoic bowel, echogenic intracardiac focus, and any major abnormality. The absence of any marker on a second trimester scan conveys a 60-80% reduction in prior risk of Down syndrome based on advanced maternal age or serum screen risk. The presence of sonographic markers, either singly or in combination, will raise the baseline risk of Down syndrome using likelihood ratios calculated for each individual marker. Using this approach, approximately 75% of fetuses with Down syndrome can be identified by modifying the patient's baseline risk according to the results of the ultrasound. The second trimester scan will likely continue to play an important role in the future in the detection of aneuploidy.
基因超声检查是对孕中期胎儿进行的超声检查，它不仅能评估胎儿是否存在结构畸形，还能寻找胎儿唐氏综合征的超声标记物。构成基因超声检查的主要标记物包括颈部褶皱、股骨和肱骨短小、肾盂扩张、肠管回声增强、心内强回声光斑以及任何重大异常。孕中期扫描未发现任何标记物，基于孕妇高龄或血清筛查风险，可使先前唐氏综合征的风险降低60 - 80%。超声标记物单独或组合出现时，将使用为每个个体标记物计算的似然比提高唐氏综合征的基线风险。采用这种方法，根据超声检查结果调整患者的基线风险，大约75%的唐氏综合征胎儿能够被识别出来。孕中期扫描在未来非整倍体检测中可能会继续发挥重要作用。
