Conte GL et al. – The study evaluated the use of non–invasive prenatal testing using cell–free circulating fetal deoxy ribonucleic acid (cfDNA) for screening 3 main autosomal fetal trisomies in twin pregnancies. As cfDNA demonstrated high success rate and performance in twin fetal pregnancies without fetal ultrasound abnormalities, it can be considered as a first– or second–line screening test in routine practice.

Methods

• A total of 492 patients with twin pregnancies without fetal ultrasound anomalies were offered cfDNA testing as a first–line screening test or following serum screening in clinical practice.
• Data were collected prospectively, followed by retrospective analysis of cfDNA using parallel sequencing.

Results

• A total of 377 and 115 patients underwent the test as first–line (following first–trimester scan) and following serum screening, respectively.
• Overall, 78.8% of the pregnancies were dichorionic–diamniotic, and the test failed in 2.9% of 420 pregnancies with available outcomes.
• Maternal weight was shown to be a significant independent predictor of test failure; however, result was achieved in 10 cases following redraw.
• CfDNA identified all 3 cases of trisomy 21 (99.8% specificity) and the only case of trisomy 18.