This suggests that fetal aneuploidy may underlie the losses in th

This suggests that fetal aneuploidy may underlie the losses in the vanishing twin cohort. Vanishing

twin and ongoing twin pregnancies could not be distinguished by fetal fractions. Of note, algorithm estimates of fetal fraction are based on a methodology validated in singleton pregnancies, and have not been independently validated in twin pregnancies. Ongoing clinical studies are focused on validating aneuploidy risk determination in multifetal pregnancies using this SNP-based technology. It is unclear how long after demise the placenta from a vanished twin may RAD001 supplier contribute fetal cfDNA to maternal circulation. This is likely governed by the rate of placental tissue autolysis and the gestational

age of the fetus at the time of demise. Studies in singleton pregnancies have shown that fetal cfDNA levels were 5-fold higher in women at the time of clinical recognition of spontaneous abortion than in women of the same gestational age with an ongoing pregnancy,41 and remained elevated for at least 7 days after Osimertinib in vitro spontaneous abortion diagnosis.42 Further, this effect was more pronounced in chromosomally abnormal spontaneous abortions than in spontaneous abortions with a normal karyotype.42 As such, it is quite possible that in a multifetal pregnancy there may be a similarly increased cfDNA contribution from a vanished twin immediately following the loss, thus compromising cfDNA screening results for the viable twin. In the results reported here, fetal cfDNA from a vanished twin was detectable for up to 8 weeks following co-twin demise. Thus, there is the potential for vanished twins to influence NIPT results long after co-twin demise. A limitation of this study was incomplete follow-up, reflecting the reality that many patients do not receive a first-trimester Methisazone ultrasound or may transfer care. Nevertheless, where data were reported,

the presence of additional fetal haplotypes determined by NIPT was confirmed in the vast majority of cases by ultrasound detection of a multifetal pregnancy or karyotype confirmation of fetal triploidy. This SNP-based NIPT identified vanishing twin, unrecognized ongoing twin, and triploid pregnancies. Identification of partial (triploidy) and complete molar pregnancies is important because of the substantial clinical implications for patients, including the risk for gestational trophoblastic neoplasia and choriocarcinoma. As vestigial placental tissue from a lost twin can contribute fetal cfDNA to maternal circulation for weeks postdemise, identification of vanishing twin pregnancies is critical to avoid incorrect NIPT results and subsequent unnecessary invasive procedures when non-SNP-based NIPT methods are used.

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