Hill L M, Guzick D, Belfar H L, Hixson J, Rivello D, Rusnak J
Department of Ultrasound, University of Pittsburgh, Pennsylvania.
Obstet Gynecol. 1989 Oct;74(4):620-3.
The biparietal diameter (BPD)/femur length ratio, nuchal skin thickening, and measured-to-expected femur length ratio have been suggested as sonographic predictors of Down syndrome. In an effort to validate these parameters, we compared their individual and combined prevalence in 22 fetuses with Down syndrome. Using our normative data, the sensitivity and specificity of the BPD/femur length ratio were 36.4 and 93.4%, respectively. Assuming an incidence of Down syndrome in the general population of one in 1000, the estimated positive predictive value was 0.6%. When the BPD/femur length ratio, nuchal skin thickening, and measured-to-expected femur length ratio were combined, the sensitivity was improved (36.4 versus 45.5%) without significantly altering the specificity (93.4% versus 92.3%). A large prospective study is required to verify the utility of sonographic predictors of Down syndrome before their application can be recommended.
双顶径（BPD）/股骨长度比值、颈部皮肤增厚以及实测股骨长度与预期股骨长度比值已被提出作为唐氏综合征的超声预测指标。为了验证这些参数，我们比较了它们在22例唐氏综合征胎儿中的个体及联合患病率。根据我们的正常数据，BPD/股骨长度比值的敏感性和特异性分别为36.4%和93.4%。假设一般人群中唐氏综合征的发病率为千分之一，估计的阳性预测值为0.6%。当将BPD/股骨长度比值、颈部皮肤增厚和实测股骨长度与预期股骨长度比值联合使用时，敏感性有所提高（36.4%对45.5%），而特异性没有显著改变（93.4%对92.3%）。在推荐应用唐氏综合征的超声预测指标之前，需要进行一项大型前瞻性研究来验证其效用。
