Background Cordocentesis in our practice is most commonly indicated for rapid karyotyping in the second or third trimester and is regarded as the gold standard for foetal chromosomal aberration diagnosis in pregnancies at high risk for chromosomal abnormalities. In this study, we investigated 3387 umbilical cord blood samples for karyotyping from pregnant women who underwent cordocentesis and explored the pregnancy outcomes of foetal sex chromosome mosaicism and chromosomal polymorphism. Results Out of the 3387 samples, 182 abnormal karyotypes were detected. Ultrasound soft markers were the most common prenatal diagnostic indication, but the detection rate of abnormal karyotypes was 2.02%, while it was 46.97% in the genome-wide NIPT-positive group. The rate of aneuploidy was lower in the soft marker group than in the other groups. Out of 16 cases with sex chromosome mosaicism, three pregnant women with foetuses with a lower proportion of sex chromosome mosaicism delivered healthy foetuses; the foetus with karyotype 46,X,i(Y)(q10)[20]/45,X[6] showed unclear genitals. Three foetuses with chromosomal polymorphisms had postnatal disorders. Conclusions NIPT should not be recommended as the first-tier screening for chromosomal aberration for pregnancies with ultrasound soft markers or pathological ultrasound findings, but NIPT can be considered an acceptable alternative for pregnancies with contraindications to cordocentesis or the fear of procedure-related foetal loss. Mosaicism found in amniotic fluid cell culture requires further cordocentesis for karyotype confirmation, and the continuation of pregnancy is safe when a normal karyotype is identified in foetal blood culture. Further genetic testing and parental karyotype analysis are needed for foetal chromosomal polymorphisms.

中文翻译：

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3387例染色体异常高危孕妇脐带血的细胞遗传学分析。

背景 在我们的实践中，脐带穿刺术最常用于妊娠中期或晚期的快速核型分析，被认为是染色体异常高风险妊娠中胎儿染色体畸变诊断的金标准。在这项研究中，我们调查了接受脐带穿刺术的孕妇的 3387 份脐带血样本进行核型分析，并探讨了胎儿性染色体嵌合和染色体多态性的妊娠结局。结果3387份样本中，检出异常核型182份。超声软标志物是最常见的产前诊断指征，但异常核型的检出率为2.02%，而在全基因组NIPT阳性组中为46.97%。软标记组的非整倍性发生率低于其他组。16例性染色体嵌合体病例中，3例性染色体嵌合体比例较低的孕妇产下健康胎儿；核型为46,X,i(Y)(q10)[20]/45,X[6]的胎儿生殖器不清晰。三个具有染色体多态性的胎儿患有产后疾病。结论 对于有超声软标志物或病理超声发现的妊娠，不应推荐 NIPT 作为染色体畸变的一级筛查，但对于有脐带穿刺禁忌症或担心与手术相关的胎儿丢失的妊娠，NIPT 可被视为可接受的替代方法。羊水细胞培养中发现的嵌合体需要进一步进行脐带穿刺以确认核型，并且在胎儿血培养中发现正常核型时继续妊娠是安全的。