Abstract
BackgroundPreimplantation genetic screening (PGS) is increasingly utilized as an adjunct procedure to IVF. Recently healthy euploid live birth were reported following transfer of mosaic embryos. Several recent publications have surmised that the degree of trophectoderm (TE) mosaicism in transferred embryos is predictive of ongoing pregnancy and miscarriage rates.MethodsThis is a corrected analysis of previously published retrospective data on vitro fertilization (IVF) cycle outcomes involving replacement of 143 mosaic and 1045 euploid embryos tested by PGS, utilizing high-resolution next-generation sequencing (NGS) of TE and determination of percentages of mosaicism. Receiver operating curves (ROCs) and measurement of area under the curve (AUC) were used to evaluated the accuracy of the predictor variable, proportion of aneuploid cells in a TE biopsy specimen, with IVF outcomes, ongoing pregnancy and miscarriage rates.ResultsConfirming findings of the previously published report we also found higher ongoing pregnancy rates (63.3% vs. 39.2%) and lower miscarriage rates (10.2% vs. 24.3%) with euploid embryo transfers than with mosaic embryo transfer. There, however, were no significant differences in ongoing pregnancy or miscarriage rates among mosaic embryo transfers at any threshold of aneuploidy. Based on AUC, TE biopsies predicted ongoing pregnancy for euploid, as well as mosaic embryos, in a range of 0.50 to 0.59 and miscarriage in a range from 0.50 to 0.66ConclusionsDegree of TE mosaicism was a poor predictor of ongoing pregnancy and miscarriage.
Highlights
Preimplantation genetic screening (PGS) is increasingly utilized as an adjunct procedure to IVF
Like array comparative genome hybridization, single-nucleotide polymorphism array, and quantitative polymerase chain reaction lack capacity to detect mosaicism in a single TE biopsy, next-generation sequencing (NGS), which currently detects mosaicism in excess of 20%, is the only technique recommended by Preimplantation Genetic Diagnosis International Society (PGDIS) [3]
Mosaic embryos, at 20–80% range aneuploidy in the TE sample, may be potentially transferred, though the PGDIS notes that such transfers be performed with caution and only in absence of euploid embryos
Summary
Preimplantation genetic screening (PGS) is increasingly utilized as an adjunct procedure to IVF. Healthy euploid live birth were reported following transfer of mosaic embryos. Preimplantation genetic screening (PGS), renamed by some as preimplantation genetic testing for aneuploidy (PGT-A), is increasingly utilized as ad-on to vitro fertilization (IVF). Utilizing NGS, embryos with less than 20% aneuploidy in the TE sample are, considered euploid; while those between 20. PGDIS guidelines suggest that embryos designated as euploid can be freely transferred, while embryos designated as aneuploid should not be transferred and, discarded [3]. Mosaic embryos, at 20–80% range aneuploidy in the TE sample, may be potentially transferred, though the PGDIS notes that such transfers be performed with caution and only in absence of euploid embryos. The society suggested an empirical hierarchy for such transfers, based on the specific aneuploidies reported in embryos [3]
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