唐氏综合征产前血清学筛查临界值的分析

Critical Values of Double Test of Down Syndrome in Second Trimester Pregnancy

目的探讨妊娠中期孕妇血清二联法筛查唐氏综合征高危切割值1∶380与1∶270的筛查价值。方法采用化学发光法对11 368例孕妇妊娠中期血清进行二联法检测,计算唐氏综合征高危风险值,比较高危切割值1∶380及1∶270对胎儿染色体异常或胎儿丢失的检出率差异。结果高危切割值为1∶380时,有941例为唐氏高危,筛查阳性率为8.28%(941/11 368),随访847例,其中确诊21三体4例,21三体阳性预测值为0.47%(4/847);胎儿有临床意义的其他染色体异常4例:1例18三体,1例13三体,1例45X,1例45X/46XX(5∶95),占高危总数的0.47%(4/847)。高危切割值为1∶270时,有521例为唐氏高危,筛查阳性率为4.58%(521/11 368),随访458例,上述8例胎儿染色体异常的孕妇均在其中,21三体阳性预测值为0.87%(4/458);胎儿有临床意义的其他染色体异常4例,占高危总数的0.87%(4/458)。高危切割值为1∶380时,唐氏髙危孕妇中因其他原因(死胎、胎儿畸形、宫内发育迟缓)引/流产者共计15例,新生儿畸形3例;以1∶270为临界值,唐氏髙危孕妇中因其他原因引/流产者共计13例,新生儿畸形2例,筛查值>1∶270与筛查值>1∶380的孕妇其胎儿丢失和新生儿畸形的发生率间差异无统计学意义(χ2=1.595,P=0.207)。结论将高危切割值定在1∶270,筛查阳性率降低的同时,漏诊率未显著增加,更具临床筛查价值。

Objective To explore the values of high - risk cut - off value 1 ： 380 and 1 ： 270 in screening Down syndrome （DS） by serum double test in second trimester pregnancy. Methods Chemiluminescence method was used to detect, by double test, the serum of 11 368 women in second trimester pregnancy. Tbe high - risk value of DS was calculated, and the critical values were set at 1：380 and 1 ： 270, respectively, and their cut - off values were compared in detecting fetal chromosomal abnormalities and fetal loss. Results When cut - off value at 1： 380, high - risk of DS was detected in 941 pregnancy women, with a positive rate of 8.28% （941/11 368） , 847 were followed up, including 4 confirmed as tfisomy 21, and the predictive value of trisomy 21 was 0. 47% （4/847）. Four foetus had other chromosome abnormalities with clinical significance： 1 trisomy 18, 1 trisomy 13, 1 45X, 1 45X/46XX （5：95）, accounting for 0. 47% （4/847）. When cut -off value set at 1：270, 521 subjects had high risk, the positive rate was 4.58% （521/11 368） , 458 were followed up, including the above -mentioned 8 foetus with chromosome abnormalities; the trisomy 21 positive predictive value was 0. 87% （4/458） ; 4 foetus had other chromosome abnormalities with clinical significance, accounting for 0. 87% （4/458） . When cut - off value at 1： 380, 15 DS highrisk pregnancy women had induced labor/abortion due to other causes （fetal death, malformation, intrauterine growth retardation） , 3 had neonatal malformation. Taking 1：270 as critical value, a total of 13 DS high -risk pregnancy women had induced labor/abortion due to other causes, 2 had neonatal malformation. There was not significant difference in fetus loss and neonatal malformation between pregnancy women with screening values 〉 1：270 and 〉 1：380 （ Х^2 = 1. 595, P = 0. 207）. Conclusion When cut - off value set at 1 ： 270, screening positive rate decreases but misdiagnosis rate does not increase, which is of more clinical screening values.