无创产前检测在双胎消失孕妇中的应用价值

目的:分析无创产前检测（noninvasive prenatal testing，NIPT）在双胎消失（vanishing twin，VT）孕妇中的应用价值。方法:回顾性分析2017年1月至2020年12月在北京大学第三医院进行NIPT的VT孕妇164例，收集所有孕妇VT发生孕周、NIPT结果及采血时间、产前诊断结果以...

Clinical value of noninvasive prenatal testing in vanishing twin pregnancies

Objective To analyze the clinical value of noninvasive prenatal testing(NIPT)in vanishing twin(VT)pregnancies.Methods A total of 164 VT pregnancies that underwent NIPT in Peking University Third Hospital from January 2017 to December 2020 were enrolled.Gestational age at onset of vanishing,results of NIPT and invasive prenatal diagnosis,blood sampling time points,and pregnancy outcomes were retrospectively analyzed using two independent samples t test and Chi-square test.Results(1)Of the 164 cases,six had positive results for NIPT,but negative results for karyotype analysis or single nucleotide polymorphism genotyping,with a false positive rate of 3.7%(6/164)for NIPT and all of them were delivered at term.Four pregnancies terminated in the second trimester,including two fetal malformation cases and one unexplained intrauterine death whose single nucleotide polymorphisms results are all normal and one inevitable abortion case due to premature rupture of membrane who refused amniocentesis.The other 154 women all gave birth to normal phenotype babies including 12 preterm ones.(2)The false-positive rate of NIPT was lower in VT pregnancies diagnosed at less than eight gestational weeks than those diagnosed after[1.5%(2/134)vs 13.3%(4/30),χ²=6.68,P=0.010].The false-positive rate was 6.9%(4/58)in women diagnosed at or below eight weeks between the occurrence of VT and blood sampling and was 1.9%(2/106)in those with interval more than eight weeks,but without significant difference(χ²=1.44,P=0.231).Conclusions Although VT pregnancies exist false-positive results in NIPT,screening is still recommended based on fully informed consent to reduce unnecessary invasive prenatal diagnosis.The earlier the onset of VT,the lower the NIPT false positive rate,but whether extending the sampling interval would reduce the risk of false-positive needs further study.