Objectives Recent years have witnessed a shift from invasive methods of prenatal screening to non-invasive strategies. Accordingly, non-invasive prenatal testing (NIPT) using cell-free fetal DNA in maternal plasma has gained a considerable deal of interest from both geneticists and obstetricians. Efficacy of this method in identification of common aneuploidies has been extensively assessed in singleton pregnancies. However, a limited number of studies have addressed the twin pregnancies. In this context, the present study is aimed at identification of the efficacy of NIPT in twin pregnancies. Methods NIPT was performed on twin pregnancies to screen trisomies 13, 18 and 21. Pregnant women referring to Nilou Clinical Laboratory between March 2016 and December 2018 were included in this research. Results In the current study, a total 356 twin pregnancies were screened in search for trisomies 13, 18 and 21. 6 cases exhibited positive NIPT results in which the presence of trisomies 13, 18 and 21 was confirmed by fetal karyotype in 1, 2 and 2 cases, respectively. One twin pregnancy showed normal karyotype. The combined false-positive rate for these trisomies was 0.28%. No false negative case was observed. The combined sensitivity and specificity of NIPT in twin pregnancies were 100 and 99.7%, respectively. Conclusion The results of the current study verify the feasibility, sensitivity and specificity of NIPT in twin pregnancies.

中文翻译：

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无创产前检查可筛查双胎妊娠中常见的三体性。

目标 近年来见证了从侵入性产前筛查方法向非侵入性策略的转变。因此，在母体血浆中使用无细胞胎儿 DNA 的无创产前检测 (NIPT) 引起了遗传学家和产科医生的极大兴趣。这种方法在鉴定常见非整倍体方面的功效已在单胎妊娠中进行了广泛评估。然而，有限数量的研究涉及双胞胎妊娠。在这种情况下，本研究旨在确定 NIPT 在双胎妊娠中的疗效。方法对双胎妊娠进行NIPT筛查13、18和21三体。本研究纳入2016年3月至2018年12月期间到尼楼临床实验室的孕妇。结果 在目前的研究中，共筛查 356 例双胎妊娠，寻找 13、18 和 21 三体。6 例 NIPT 结果呈阳性，其中 13、18 和 21 三体的存在分别由 1、2 和 2 例的胎儿核型证实。一对双胞胎妊娠显示正常核型。这些三体的综合假阳性率为 0.28%。没有观察到假阴性病例。双胎妊娠中 NIPT 的综合敏感性和特异性分别为 100% 和 99.7%。结论本研究结果验证了NIPT在双胎妊娠中的可行性、敏感性和特异性。一对双胞胎妊娠显示正常核型。这些三体的综合假阳性率为 0.28%。没有观察到假阴性病例。双胎妊娠中 NIPT 的综合敏感性和特异性分别为 100% 和 99.7%。结论本研究结果验证了NIPT在双胎妊娠中的可行性、敏感性和特异性。一对双胞胎妊娠显示正常核型。这些三体的综合假阳性率为 0.28%。没有观察到假阴性病例。双胎妊娠中 NIPT 的综合敏感性和特异性分别为 100% 和 99.7%。结论本研究结果验证了NIPT在双胎妊娠中的可行性、敏感性和特异性。