介入性核型检测联合超声在无创胎儿非整倍体异常病例中的应用

目的探讨介入性核型检测联合超声在胎儿无创非整倍体筛查异常病例中的应用。 方法收集2015年10月至2017年12月在徐州市中心医院产前诊断中心进行无创产前基因检测（NIPT）的单胎孕妇2640例为研究对象，年龄18~43岁，孕周13~25周，对检测42例异常染色体孕妇进行产前诊断并对妊娠结局进行跟踪统计分析。介入性核型检查与NIPT对胎儿染色体异常结果检测效能的比较采用McNemar χ²检验和Kappa一致性检验。 结果NIPT异常者42例：其中31例常染色体异常、10例性染色体异常及同时有常染色体及性染色体异常1例，常染色体异常包括：17例21-三体高风险，9例提示18-三体高风险，染色体7-三体、15-三体及13-三体各1例，7号染色体重复51Mb 1例，16号染色体异常1例；10例性染色体异常中45，XO 6例；47，XYY 2例，47，XXX 1例，性染色体XX与XXX嵌合1例。42例中1例放弃产前诊断直接引产，36例羊水穿刺，5例脐静脉穿刺，确诊21-三体14例、18-三体7例和47，XYY 1例，余320~400染色体条带水平未发现异常，其中有12例21-三体和7例18-三体胎儿有超声结构改变，余无超声结构改变，共22例引产，1例流产，19例新生儿结局良好。NIPT对胎儿染色体异常阳性率明显高于介入性核型检查（P<0.05）。 结论NIPT对21-三体和18-三体检出率较高，但对于常染色体和性染色体仍存在一定的假阳性，NIPT发现异常的孕妇需进行胎儿结构超声及介入性核型检查，避免对无辜胎儿的伤害。

Application of interventional karyotype examination combined with ultrasound in diagnosis of fetal chromosome aneuploidy detected by noninvasive prenatal test

ObjectiveTo explore the application of interventional karyotype examination combined with ultrasound in the diagnosis of fetal chromosome aneuploidy detected by the noninvasive prenatal test (NIPT). MethodsForty-two cases with abnormal NIPT results were enrolled from October 2015 to December 2017 in prenatal diagnosis center of Xuzhou Center Hospital. Further invasive prenatal examinations such as amniotic fluid or cord blood puncture were accomplished for the definite diagnosis. Conventional Giemsa (G) banding karyotype analyses were conducted for the fetus and parents and all cases were followed for pregnancy outcomes. Comparison of the efficiency of interventional karyotype test and NIPT in the detection of fetal chromosomal abnormalities was made by McNemar χ² and Kappa consistency tests. ResultsOf the 42 cases with abnormal NIPT results, 31 had autosomal abnormalities, 10 had sex chromosome abnormalities, and 1 had both autosomal and sex chromosome abnormalities. The autosomal abnormalities included 17 cases at high risk for 21-trisomy, 9 cases at high risk for 18-trisomy, and 1 case each of 7-trisomy, 15-trisomy, 13-trisomy, chromosome 7 with 51Mb repeated segment, and chromosome 16 with abnormality. The sex chromosome abnormalities included 6 cases of 45, XO, 2 cases of 47, XYY, and 1 case each of chromosome 47, XXX and 47, XXX with XX. Of the 42 patients, 1 gave up prenatal diagnosis and selected induction of labor, 36 underwent amniocentesis, and 5 underwent umbilical vein puncture. Finally, 14 cases of 21-trisomy, 7 cases of 18- trisomy, and 1 case of 47, XYY were diagnosed. Among the 14 definite cases of 21-trisomy, 12 were complicated with ultrasound structural abnormalities, while the 7 definite cases of 18-trisomy had totally ultrasound structural abnormalities. The other cases showed no abnormalities in the chromosomes of 320-400 bands and had no ultrasound structure changes. A total of 22 cases underwent induced labor, 1 case had abortion, and the other 19 cases were followed with good neonatal outcomes. Therefore, the positive rate of fetal chromosome abnormality detected by the NIPT was significantly higher than that by interventional karyotype examination (P<0.05). ConclusionNIPT has a high detection rate for 21-trisomy and 18-trisomy, but there are still false positives for autosomal and sex chromosomes. Fetal structure ultrasound and interventional karyotype examination are still necessary for pregnant women with abnormal NIPT results to avoid harm to innocent fetuses.