探讨胎儿唐氏综合征(DS)的不同产前诊断指征，在中孕期产前诊断中的应用价值。

选择2011年1月1日至2014年12月31日于广西壮族自治区妇幼保健院/儿童医院/妇产医院接受中孕期羊膜腔穿刺术的18 693例孕妇的临床病历资料为研究对象。本组接受中孕期羊膜腔穿刺术孕妇的DS产前诊断指征包括：高龄(≥35岁，11 664例)，血清学筛查高风险(酶联免疫法检测21-三体综合征风险值≥1/270、18-三体综合征风险值≥1/350，4 226例)，胎儿超声检查结果异常(620例)，夫妇一方染色体异常(651例)，夫妇双方或一方为地中海贫血患者(782例)，以及不良孕产史(748例)与无创产前检测(NIPT)结果呈阳性(2例)。上述进行中孕期羊膜腔穿刺术的胎儿DS产前诊断指征均为单一指征，无交叉。羊膜腔穿刺取羊水细胞进行遗传学检查，对胎儿DS进行确诊。对具有胎儿DS不同产前诊断指征的中孕期孕妇的胎儿DS检出例数及检出率进行比较，并对检出率进行统计学分析。本研究遵循的程序符合广西壮族自治区妇幼保健院/儿童医院/妇产医院人体试验委员会制定的伦理学标准，得到该委员会批准，羊膜腔穿刺术前均与受试者签署知情同意书。

本组18 693例孕妇于中孕期进行羊膜腔穿刺，共计检出151例DS胎儿，检出率为0.8%(151/18 693)。对中孕期DS胎儿的不同产前诊断指征与胎儿DS检出例数及检出率的研究结果显示，分别于11 664例高龄、4 226例血清学筛查高风险、620例胎儿超声检查结果异常、651例夫妇一方染色体异常、782例夫妇双方或一方为地中海贫血患者、748例不良孕产史及2例NIPT结果呈阳性的孕妇中，检出DS胎儿45、79、15、2、5、3及2例，胎儿DS检出率分别为0.4%、1.9%、2.4%、0.3%、0.6%、0.4%及100.0%。对上述中孕期具有胎儿DS不同产前诊断指征孕妇的胎儿DS检出率比较，差异有统计学意义(χ²＝111.83，P<0.001)。

血清学筛查高风险、高龄(≥35岁)妊娠及胎儿超声检查结果异常，是中孕期产前筛查胎儿DS的重要产前诊断指征。同时，应重视夫妇一方染色体异常和地中海贫血等产前诊断指征，减少出生缺陷儿的出生率。

To analyze the application value of different prenatal diagnosis indications of fetal Down syndrome (DS) in the prenatal diagnosis during the second trimester.

From 1st January 2011 to 31st December 2014, clinical data of 18 693 cases of pregnant women who received amniocentesis in Maternal and Child Hospital/Children′s Hospital/Obstetrics and Gynecology Hospital of Guangxi Zhuang Autonomous Region were selected as research subjects. The prenatal diagnosis indications of DS among 18 693 cases of pregnant women who received amniocentesis during the second trimester included: advanced maternal age (≥35 years old, 11 664 cases), high risk of serum screening (the risk value of trisomy-21 syndrome ≥ 1/270, trisomy-18 syndrome ≥ 1/350, 4 226 cases), abnormal fetal ultrasound examination results (620 cases), one of the couple with chromosomal abnormalities (651 cases), and one of the couple or two with mediterranean anemia (782 cases), abnormal pregnancy history (748 cases) and noninvasive prenatal test (NIPT) positive (2 cases). All the prenatal diagnosis indications of DS were uncrossed. Amniotic fluid cells were collected by amniocentesis to take the genetics examination, in order to final diagnose the fetal DS. The number and detection rate of fetal DS among pregnant women during the second trimester with the above-mentioned prenatal diagnosis indications of DS were compared, and the detection rate of fetal DS was analyzed by statistical method. The study protocol was approved by the Ethical Review Board of Investigation in Maternal and Child Hospital/Children′s Hospital/Obstetrics and Gynecology Hospital of Guangxi Zhuang Autonomous Region. Informed consent was obtained from each participate before receiving amniocentesis.

A total of 18 693 cases of amniotic fluid were detected, and 151 cases were detected as fetal DS, the detection rate was 0.8% (151/18 693). The results of amniocentesis showed that, among 11 664 cases of pregnant women with advanced maternal age, 4 226 cases with high risk of serum screening, 620 cases with abnormal fetal ultrasound examination results, 651 cases with one of the couple with chromosomal abnormalities, 782 cases with one of the couple or two with mediterranean anemia, 748 cases with abnormal pregnancy history and 2 cases with NIPT positive, 45, 79, 15, 2, 5, 3 and 2 cases were detected as fetal DS, respectively. And the detection rate of fetal DS was 0.4%, 1.9%, 2.4%, 0.3%, 0.6%, 0.4% and 100.0%, respectively. There was statistical difference among the fetal DS detection rate of different prenatal diagnosis indications of fetal DS (χ²=111.83, P<0.001).

High-risk of serum screening, advanced maternal age (≥35 years old), and abnormal ultrasonic testing results are important prenatal diagnosis indications of fetal DS. At the same time, we should pay attention to the prenatal diagnosis indications of one of the couple with chromosomal abnormalities or mediterranean anemia, in order to reduce the rate of birth defects.