Clinica Eccos, Belo Horizonte, Minas Gerais, Brazil,
Arch Gynecol Obstet. 2012 May;285(5):1263-70. doi: 10.1007/s00404-011-2175-4. Epub 2011 Dec 20.
To establish fetal nasal bone length cut-off points for first trimester aneuploidy screening based on a normal curve of a Brazilian population.
The following tests were proposed: presence or absence of the nasal bone (NB); 2.5 and 5.0 NB percentiles relative to the normal curve; and 0.70, 0.75 and 0.80 multiples of the median (MoM) values defined in the receiver operating characteristic (ROC) curve. Nasal Bone tests were based on positive and negative likelihood ratio value detection rates (LR); the confidence interval was 95% in all tests. Cases in which ultrasonographic images of the NB were absent were not taken into account when evaluating the 2.5 and 5.0 percentiles and the 0.70, 0.75 and 0.80 MoM.
The sample consisted of 571 fetuses (10-14 weeks). After exclusions (11) and loss of follow-up (53), the study sample was reduced to 507 patients. There were 23 Down syndrome patients among 41 aneuploid fetuses. The sensitivity of the qualitative NB test (absent vs. present) was 34.1%, and the specificity was 99.1% (+LR 37.89, -LR 0.66). An image of the nasal bone was absent in 52.2% of fetuses with the Down syndrome (+LR 58.00, -LR 0.48).
The best tool for aneuploidy screening was the qualitative NB test (absent vs. present). Ultrasonography of the NB is a component of aneuploidy screening, and should not be used alone.
基于巴西人群的正常曲线，建立早孕期三体综合征筛查的胎儿鼻骨长度截断值。
提出了以下检测方法：鼻骨（NB）的存在或缺失；相对于正常曲线的 NB 的 2.5 和 5.0 百分位数；以及在接收者操作特征（ROC）曲线中定义的 0.70、0.75 和 0.80 中位数倍数（MoM）值。鼻骨检测基于阳性和阴性似然比检测率（LR）；所有检测的置信区间均为 95%。在评估 2.5 和 5.0 百分位数以及 0.70、0.75 和 0.80 MoM 时，不考虑 NB 超声图像缺失的病例。
样本包括 571 例胎儿（10-14 周）。排除（11）和失访（53）后，研究样本减少至 507 例。在 41 例非整倍体胎儿中，有 23 例唐氏综合征患者。定性 NB 检测（缺失与存在）的敏感性为 34.1%，特异性为 99.1%（+LR 37.89，-LR 0.66）。在唐氏综合征胎儿中，52.2%的胎儿 NB 图像缺失（+LR 58.00，-LR 0.48）。
筛查非整倍体的最佳工具是定性 NB 检测（缺失与存在）。NB 超声是筛查非整倍体的一部分，不应单独使用。
