Bevilacqua E, Gil M M, Nicolaides K H, Ordoñez E, Cirigliano V, Dierickx H, Willems P J, Jani J C
Department of Obstetrics and Gynecology, University Hospital Brugmann, Brussels, Belgium.
Ultrasound Obstet Gynecol. 2015 Jan;45(1):61-6. doi: 10.1002/uog.14690. Epub 2014 Dec 4.
To report clinical implementation of cell-free DNA (cfDNA) analysis of maternal blood in screening for trisomies 21, 18 and 13 in twin pregnancies and examine variables that could influence the failure rate of the test.
cfDNA testing was performed in 515 twin pregnancies at 10-28 weeks' gestation. The failure rate of the test to provide results was compared with that in 1847 singleton pregnancies, and logistic regression analysis was used to determine which factors among maternal and pregnancy characteristics were significant predictors of test failure.
Failure rate of the cfDNA test at first sampling was 1.7% in singletons and 5.6% in twins. Of those with a test result, the median fetal fraction in twins was 8.7% (range, 4.1-30.0%), which was lower than that in singletons (11.7% (range, 4.0-38.9%)). Multivariable regression analysis demonstrated that twin pregnancy, higher maternal weight and conception by in-vitro fertilization provided significant independent prediction of test failure. Follow-up was available in 351 (68.2%) of the twin pregnancies and comprised 334 with euploid fetuses, 12 discordant for trisomy 21 and five discordant for trisomy 18. In all 323 euploid cases with a result, the risk score for each trisomy was < 1:10 000. In 11 of the 12 cases with trisomy 21 and in the five with trisomy 18, the cfDNA test gave a high-risk result, but in one case of trisomy 21, the score was < 1:10 000.
In twin pregnancies screening by cfDNA testing is feasible, but the failure rate is higher and detection rate may be lower than in singletons.
报告孕妇外周血游离DNA（cfDNA）分析在双胎妊娠21、18和13三体综合征筛查中的临床应用情况，并探讨可能影响检测失败率的因素。
对515例妊娠10 - 28周的双胎妊娠进行cfDNA检测。将该检测结果未得出的失败率与1847例单胎妊娠的情况进行比较，并采用逻辑回归分析确定孕产妇和妊娠特征中的哪些因素是检测失败的显著预测指标。
单胎妊娠首次采样时cfDNA检测的失败率为1.7%，双胎妊娠为5.6%。在获得检测结果的人群中，双胎妊娠的胎儿游离DNA比例中位数为8.7%（范围4.1% - 30.0%），低于单胎妊娠（11.7%（范围4.0% - 38.9%））。多变量回归分析表明，双胎妊娠、孕产妇体重较高以及体外受精受孕是检测失败的显著独立预测因素。351例（68.2%）双胎妊娠有随访结果，其中334例胎儿为整倍体，12例21三体不一致，5例18三体不一致。在所有323例有结果的整倍体病例中，每种三体的风险评分均<1:10000。在12例21三体病例中的11例以及5例18三体病例中，cfDNA检测给出了高风险结果，但1例21三体病例的评分<1:10000。
在双胎妊娠中，通过cfDNA检测进行筛查是可行的，但失败率较高，且检测率可能低于单胎妊娠。
