Biagiotti R, Periti E, Cariati E
Department of Gynaecology and Obstetrics, University of Florence, Italy.
Prenat Diagn. 1994 Jun;14(6):429-34. doi: 10.1002/pd.1970140603.
The aim of the study was to assess the value of sonographic measurement of fetal humerus and femur lengths in the second trimester as a screening tool for Down syndrome (DS). We reviewed retrospectively fetal sonographic biometry made at the time of amniocentesis between 15 and 19 weeks. The study group consisted of 27 DS fetuses. The control group comprised 500 normal fetuses chosen randomly. The expected humeral and femoral lengths for a given biparietal diameter were estimated by linear regression equations from the 500 normal fetuses. Receiver operating characteristic curve analysis was performed to evaluate both the detection rate and the false-positive rate of different cut-off values of measured to expected lengths ratios. The median femur and humeral lengths in DS fetuses were 0.91 times the expected values. No significant differences in the detection rate and false-positive rate were found between the humerus and femur lengths. When the humeral and femoral lengths were combined, we observed a remarkable reduction in the false-positive rate. A measured to expected length ratio of 0.91 detected 44.4 per cent of DS fetuses with 7.6 per cent false positives. These results suggest that the combination of femoral and humeral lengths may permit a more efficient use of ultrasound in screening for Down syndrome than the use of either alone.
本研究的目的是评估孕中期胎儿肱骨和股骨长度的超声测量作为唐氏综合征（DS）筛查工具的价值。我们回顾性分析了15至19周羊膜穿刺术时的胎儿超声生物测量数据。研究组包括27例DS胎儿。对照组由随机选择的500例正常胎儿组成。根据500例正常胎儿的线性回归方程，估计给定双顶径对应的肱骨和股骨预期长度。进行了受试者操作特征曲线分析，以评估测量长度与预期长度比值的不同临界值的检测率和假阳性率。DS胎儿的股骨和肱骨长度中位数为预期值的0.91倍。肱骨和股骨长度在检测率和假阳性率方面无显著差异。当将肱骨和股骨长度结合起来时，我们观察到假阳性率显著降低。测量长度与预期长度比值为0.91时，可检测出44.4%的DS胎儿，假阳性率为7.6%。这些结果表明，与单独使用股骨或肱骨长度相比，股骨和肱骨长度相结合可能会使超声在唐氏综合征筛查中得到更有效的应用。
