Objective: To evaluate the efficacy of cell free DNA (cf-DNA) screening in prenatal care by analyzing the follow-up information and pregnancy outcomes. Methods: All cf-DNA cases conducted in Women's Hospital of Nanjing Medical University from August 2011 to December 2017 were enrolled. The general information of the pregnancies, cf-DNA results, confirmatory testing results, and the follow-up results were collected. The pregnancy outcomes were analyzed in cases with low risk cf-DNA results as well as with high risk results for common trisomies, which were trisomy 21 (T21), trisomy 18 (T18), and trisomy 13 (T13). The sensitivity, specificity, positive predictive value and negative predictive value of cf-DNA screening were calculated. Results: (1) A total of 43 615 cf-DNA cases were involved, with 44 cases (0.10%, 44/43 615) test failure results, 314 cases (0.72%, 314/43 571) high risk results for common trisomies and 43 257 cases (99.27%, 43 257/43 571) low risk results. (2) Among 277 cases (88.21%, 277/314) high risk cases were successfully followed up, and 228 cases (82.31%, 228/277) underwent invasive confirmatory prenatal diagnosis. In the low risk results, 36 826 cases (85.13%, 36 826/43 257) were successfully followed up, and 572 (1.55%, 572/36 826) cases were found to have adverse pregnancy outcomes, among which 4 false negative cf-DNA results were confirmed. (3) In the 37 103 successfully followed up cf-DNA cases, the sensitivity for T21, T18, T13 were calculated as 97.96%, 96.67% and 100.00%, respectively; the specificity for T21, T18, T13 were calculated as 99.96%, 99.95% and 99.95%, respectively. The positive predictive value for T21, T18, T13 were calculated as 90.57%, 63.04% and 17.39%, respectively. The negative predictive value for T21, T18, T13 were calculated as 99.99%, 99.98% and 100.00%. Conclusions: Cf-DNA is effective in detecting common trisomies, with a high sensitivity and specificity. However, the follow-up information revealed several potential limitations in current clinical practice, such as a number of cases with high risk results rejected invasive confirmatory testing, as well as the genetic diagnostic results for most low risk cases with an adverse pregnancy outcome aren't obtained. Genetic counseling and the follow-up for all the cf-DNA cases should be emphasized in the future.
目的： 通过分析孕妇外周血游离DNA（cf-DNA）检测结果的随访资料及相关的妊娠结局，评估cf-DNA检测在产前筛查中的价值。 方法： 收集2011年8月至2017年12月于南京医科大学附属妇产医院进行cf-DNA检测的孕妇的临床资料，包括孕妇的一般情况、cf-DNA检测结果及随访结果。并分析cf-DNA检测结果为常见染色体三体（包括21三体、18三体、13三体）高风险和低风险孕妇的妊娠结局，评价cf-DNA检测的价值，包括敏感度、特异度及阳性预测值、阴性预测值。 结果： （1）本研究共纳入了43 615例行cf-DNA检测的孕妇，其中44例（0.10%，44/43 615）检测失败；检出结果为常见染色体三体高风险314例（0.72%，314/43 571），低风险43 257例（99.28%，43 257/43 571）。（2）cf-DNA检测结果为常见染色体三体高风险的314例孕妇中，277例（88.21%，277/314）完成随访，其中228例（82.31%，228/277）孕妇接受了侵入性产前诊断为低风险的43 257例孕妇中，36 826例（85.13%，36 826/43 257）完成随访，其中572例（1.55%，572/36 826）妊娠结局不良，包括4例为cf-DNA检测结果假阴性。（3）在完成随访的37 103例孕妇中，21三体、18三体、13三体的敏感度分别为97.96%、96.67%、100.00%，特异度分别为99.96%、99.95%、99.95%，阳性预测值分别为90.57%、63.04%、17.39%，阴性预测值分别为99.99%、99.98%和100.00%。 结论： cf-DNA检测在胎儿常见染色体三体的产前筛查中具有极高的敏感度和特异度，但仍有一定数量的cf-DNA检测结果为常见染色体三体高风险的孕妇拒绝行侵入性产前诊断以验证cf-DNA检测结果。常见染色体三体低风险的孕妇，因未行侵入性产前诊断，导致部分孕妇出现不良妊娠结局时，无法获得胎儿的染色体核型信息。.
Keywords: Aneuploidy; Cell-free nucleic acids; Follow-up studies; Pregnancy outcome; Prenatal diagnosis.