The performance of noninvasive prenatal testing (NIPT) in monochorionic diamniotic twin pregnancies with treatment of assisted reproductive techniques (ART)

Abstract

Introduction The objective of this research is to study the performance of noninvasive prenatal testing (NIPT) in monochorionic diamniotic twin pregnancies after the treatment of assisted reproductive technology (ART). Material & methods From March 2015 to December 2016, we provided NIPT targeting trisomy 21 (T21), 18 (T18), and 13 (T13) by sequencing cell-free DNA in maternal plasma, for 2403 chinese pregnant women with monochorionic diamniotic twin pregnancies through ART treatment. Positive NIPT results were validated by karyotyping, while negative results were interviewed after delivery. Results In total of 2403 cases, NIPT had a failure rate of 1.8% (44/2403). 7 cases of T21 were identified by NIPT and confirmed by karyotyping or follow-up interviews, among which 3 were true-positive and 4 were false-positive, making a positive predictive value as 42%. Interestingly, all the 4 false-positive cases were vanishing twins while the 3 true-positive cases were not. 6 cases of T18 were identified by NIPT, among which 5 were false-positive and 1 aborted spontaneously. 4 in the 5 T18 false-positive cases were vanishing twins. Among 2346 cases with NIPT negative results, 2179 cases (92.9%) were confirmed by follow-up survey of postnatal phenotypes, while 111 cases (4.7%) had adverse pregnant outcomes with unconfirmed reasons. The remaining 56 cases (2.4%) refused follow-up interviews. No false negative result was reported. Conclusion Our data implies that NIPT for T21 and T18 has a notable rate of false-positive results, with vanishing twins as the major cause. Nonetheless, NIPT is still a good screening approach for ART monochorionic diamniotic twin pregnancies, as no false-positive case was observed in this study. The objective of this research is to study the performance of noninvasive prenatal testing (NIPT) in monochorionic diamniotic twin pregnancies after the treatment of assisted reproductive technology (ART). From March 2015 to December 2016, we provided NIPT targeting trisomy 21 (T21), 18 (T18), and 13 (T13) by sequencing cell-free DNA in maternal plasma, for 2403 chinese pregnant women with monochorionic diamniotic twin pregnancies through ART treatment. Positive NIPT results were validated by karyotyping, while negative results were interviewed after delivery. In total of 2403 cases, NIPT had a failure rate of 1.8% (44/2403). 7 cases of T21 were identified by NIPT and confirmed by karyotyping or follow-up interviews, among which 3 were true-positive and 4 were false-positive, making a positive predictive value as 42%. Interestingly, all the 4 false-positive cases were vanishing twins while the 3 true-positive cases were not. 6 cases of T18 were identified by NIPT, among which 5 were false-positive and 1 aborted spontaneously. 4 in the 5 T18 false-positive cases were vanishing twins. Among 2346 cases with NIPT negative results, 2179 cases (92.9%) were confirmed by follow-up survey of postnatal phenotypes, while 111 cases (4.7%) had adverse pregnant outcomes with unconfirmed reasons. The remaining 56 cases (2.4%) refused follow-up interviews. No false negative result was reported. Our data implies that NIPT for T21 and T18 has a notable rate of false-positive results, with vanishing twins as the major cause. Nonetheless, NIPT is still a good screening approach for ART monochorionic diamniotic twin pregnancies, as no false-positive case was observed in this study.