Yang Xin, Zhen Li, Pan Min, Han Jin, Li Dongzhi, Liao Can
Prenatal Diagnostic Center, Guangzhou Maternal and Neonatal Hospital , Guangzhou, Guangdong , China.
J Matern Fetal Neonatal Med. 2014 Dec;27(18):1860-3. doi: 10.3109/14767058.2014.885944. Epub 2014 Feb 13.
To investigate the ratio of prenasal thickness (PT) to nasal bone length (NBL) in normal and trisomy 21 fetuses in the second and third trimester in Chinese population.
The NBL and PT were measured blindly by using 3D volumes in 143 normal fetuses and 31 trisomy 21 fetuses.
The mean PT (r = 0.83, p = 0.004) and NBL (r = 0.87, p = 0.0062) both increased with the gestation age, while the PT/NBL ratio (r = 0.12, p > 0.10) remained stable. There was significant difference between normal and trisomy 21 fetuses (p < 0.001). If we took the 95th of the normal fetuses as the cut-off value, the detection rate was only 46%. By using ROC curve to evaluate the screening value of PT/NBL ratio, the area under receiver operating characteristic (ROC) curve was 0.88 (95% confidence interval 0.81 to 0.94, p < 0.0001).
In Chinese population, the PT/NBL ratio is not a very strong ultrasound marker to predict trisomy 21 fetuses. However, it can be used as an ultrasound marker for Down syndrome screening during the second and third trimester of pregnancy.
研究中国人群中孕中期和孕晚期正常胎儿及21三体胎儿的鼻前厚度（PT）与鼻骨长度（NBL）之比。
对143例正常胎儿和31例21三体胎儿使用三维容积数据进行盲法测量NBL和PT。
平均PT（r = 0.83，p = 0.004）和NBL（r = 0.87，p = 0.0062）均随孕周增加，而PT/NBL比值（r = 0.12，p > 0.10）保持稳定。正常胎儿与21三体胎儿之间存在显著差异（p < 0.001）。若以正常胎儿的第95百分位数作为截断值，检出率仅为46%。采用ROC曲线评估PT/NBL比值的筛查价值，受试者操作特征（ROC）曲线下面积为0.88（95%置信区间0.81至0.94，p < 0.0001）。
在中国人群中，PT/NBL比值并非预测21三体胎儿的强有力超声标志物。然而，它可作为孕中期和孕晚期唐氏综合征筛查的超声标志物。
