鼻前软组织厚度产前筛查唐氏综合征的临床价值

目的 通过超声检测胎儿鼻前软组织厚度(PT),探讨鼻前软组织厚度与唐氏综合征(DS)的关系,建立超声软指标PT中位倍数(MoM)值,明确PT筛查唐氏综合征的临床价值。 方法 对2012年6月—2014年6月期间在温州市中心医院超声检查的孕16～25周的正常胎儿及DS胎儿进行PT测量,组间比较采用t检验或Wilcoxon秩和检验,并行Spearman线性相关分析,采用二次回归模型计算2组MoM(PT)值,并建立风险评估模型,观察敏感度、特异度、阳性预测值、阴性预测值、阳性似然比、阴性似然比指标。 结果 正常组PT平均值为(3.51±0.91) mm,DS组PT平均值为(5.16±0.79) mm,差异有统计学意义(t=12.23,P＜0.05);正常组胎儿PT随孕周增加而增厚,正常胎儿PT的MoM值为1.010,DS胎儿PT的MoM值为1.371。PT为单一指标筛查DS,以5%假阳性率,筛查唐氏综合征胎儿敏感度为58%,阳性预测值为0.46,阴性预测值为0.97,阳性似然比为11.63,阴性似然比为0.44;PT联合年龄高风险筛查DS,以5%假阳性率,敏感度提高到75%,阳性预测值为0.52,阴性预测值为0.98,阳性似然比为14.94,阴性似然比为0.26。 结论 鼻前软组织厚度是孕中期筛查唐氏综合征有效的遗传学超声软指标,唐氏综合征胎儿鼻前软组织厚度较正常胎儿厚。鼻前软组织厚度联合年龄高风险筛查唐氏综合征可以提高筛查敏感度,风险截断值达1/250,应建议行侵入性检查。 

Predictive role of prenasal thickness by prenatal ultrasound test for Down syndrome

Objective To detect the prenasal thickness(PT) of fetuses with prenatal ultrasound test,investigate the predictive role of prenasal thickness for fetuses with Down syndrome,and determine the multiples of the median(MoM) value of PT in ultrasonic examination,and assess the clinical value of PT in screening for Down syndrome fetuses. Mesthods PT was measured in normal and DS fetal at 16-25 weeks of gestation in our hospital from June,2012 to June,2014.The Student’s t-test or Wilcoxon rank sum test was used to compare the mean difference between the two groups.Spearman’s Rank-order Correlation was implemented to determine the correlation of two variables.The MoM(PT) value of two groups was calculated by using a quadratic model for the Trisomy risk assessment.The sensitivity,specificity,positive and negative predictive value,positive and negative likelihood ratio were observed. Results The average PT in the normal group was (3.51±0.91)mm,and in the DS group was (5.16±0.79)mm,the difference was statistically significant(t=12.23,P<0.05) PT increased with the gestational age.MoM(PT)values in DS and unaffected pregnancies were 1.371 and 1.010 MoM,respectively.Using PT alone for screening of DS,the false positive rate was 5% and the sensitivity was predicted to be 58%,the positive predictive value was 0.46,the negative predictive value was 0.97,the positive likelihood ratio was 11.63,the negative likelihood ratio was 0.44;When combining of PT with high risk age,the false positive rate was 5% and the sensitivity was increased to 75%,the positive predictive value was 0.52,the negative predictive value was 0.98,the positive likelihood ratio was 14.94,the negative likelihood ratio was 0.26. Conclusion PT is considered as the effective sonographic marker to screen Down syndrome in the second trimester.PT of fetuses with Down syndrome is thicker than that of the unaffected pregnancies.The combination of PT and pregnant women age will obviously increase the detection rate of Down syndrome fetus.When the risk cut-off levels are > or =1 in 250 for Down syndrome,the invasive examination should be performed.