Could monopronucleated ICSI zygotes be considered for transfer? Analysis through time-lapse monitoring and PGS
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The purpose of this study was to investigate the chromosomal constitution and the developmental potential of intracytoplasmic sperm injection (ICSI) deriving embryos displaying a single pronucleus at the zygote stage.
Eighty-eight embryos from single pronucleus (1PN) two polar bodies (2PB) ICSI zygotes from 64 preimplantational genetic screening (PGS) cycles (October 2012–December 2014), were retrospectively analyzed. Zygotes were cultured in a time-lapse incubator. Embryo biopsy was performed on day 3 and genetic analysis approached by array comparative genomic hybridization.
Chromosomal analysis revealed that 17% (15/88) of embryos derived from 1PN 2PB zygotes were diagnosed as euploid. After blastomere biopsy at day 3, the blastocyst rate at day 5 was 3.4% (3/88). Only 2.3% (2/88) euploid blastocysts were obtained. In two couples and after counseling and patient agreement, the transfer of a euploid blastocyst from a 1PN 2PB ICSI zygote was performed resulting in the birth of a healthy child.
These results open the possibility to consider embryos coming from 1PN 2PB ICSI zygotes for transfer when no other embryos from 2PN 2PB ICSI zygotes are available and if a PGS diagnosis of euploidy is obtained. Confirmation of biparental inheritance is strongly recommended.
KeywordsaCGH Monopronucleated zygotes 1PN PGS Time-lapse
Compliance with ethical standards
The project was approved by the institutional review board of the center.
This work was performed under the auspices of “Càtedra d’Investigació en Obstetrícia i Ginecologia” of the Department of Obstetrics, Gynecology and Reproduction, Dexeus Women’s Health (Barcelona).
Conflict of interest
The authors declare that they have no conflict of interest.
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