目的 对非侵入性产前筛查准确性的影响因素进行分析。方法 选取2015年1月至2017年11月因NIPT结果异常（多家检测公司）在我院行羊膜腔穿刺进行产前诊断的病例，共441例。根据NIPT异常结果进行分类统计。结果 441例NIPT异常结果中，包括21三体高风险149例（真阳性116例,阳性预测值78.0%），18-三体高风险49例（真阳性22例，阳性预测值45.0%），13-三体高风险24例（真阳性5例，阳性预测值21.0%），性染色体数目偏多81例（真阳性54例，阳性预测值67.0%），性染色体数目偏少53例（真阳性9例，阳性预测值17.0%），性染色体数目异常26例（真阳性9例，阳性预测值35.0%），由于微缺失、微重复例数较少，统计学意义较差，统一归类为罕见染色体异常共59例（真阳性7例，阳性预测值为12.0%）。结论 NIPT的结果受多种因素的影响（检测公司，取血孕周，孕妇年龄，BMI等），统计结果表明NIPT只是筛查手段，尚不能替代目前临床上常用的诊断手段。对于21-三体具有最高的检出率，而对于其他类型的染色体异常效果较差。此外，目前还尚未推荐NIPT用于罕见染色体非整倍体及微缺失、微重复的筛查。因此，在进行NIPT前，应明确其适用人群，加强质量控制，进一步提高其阳性预测值。产前咨询医生应明确告知患者及其家属筛查手段的局限性，并对筛查结果进行解读，以便及时获得进一步的医疗帮助。
Objective Analysis of the factors affecting the accuracy of non-invasive prenatal testing. Methods A total of 441 cases were selected for prenatal diagnosis of amniocentesis in our hospital from January 2015 to November 2017 due to the abnormal NIPT result (a number of test companies). According to the results of NIPT anomalies, the classification and statistics were carried out. Results The abnormal results of NIPT included 149 cases of trisomy 21 with high risk (116 cases of true positive, 78.0% of positive predictive value), 49 cases of high risk of trisomy 18 (22 cases of true positive, 45.0% of positive predictive value), 24 cases of high risk of trisomy 13 (5 cases of true positive, 21.0% of positive predictive value), 81 cases of excessive number of sex chromosomes (54 cases of true positive, 67.0% of positive predictive value), 53 cases of decreased number of sex chromosomes (9 cases of true positive, 17.0% of positive predictive value), 26 cases of abnormal number of sex chromosomes (9 cases of true positive, 35.0% of positive predictive value), due to the number of microdeletion/microrepeats was less, and the statistical significance was poor, 59 cases were classified as rare chromosome abnormalities (7 cases of true positive, 12.0% of positive predictive value). Conclusions The results of NIPT are affected by many factors (test company, gestational weeks of blood collection, age of pregnant women, BMI, etc.). The statistical results show that NIPT is only a screening method, which cannot replace the diagnostic methods commonly used in clinic at present. It has the highest detection rate for trisomy 21, but has poor effect on other types of chromosome abnormalities. In addition, NIPT has not been recommended for rare chromosome aneuploidy and microdeletion/microduplication screening. Therefore, before the NIPT, it is necessary to clarify the suitable population, strengthen the quality control, and further improve its positive predictive value. The prenatal counselors should clearly inform patients and their families of the limitations of screening methods and interpret the screening results in order to obtain further medical assistance in a timely manner.
