Early Embryo Cleavage and Mononucleate Blastomeres as Predictors of Embryo Implantation Potential

Abstract

To evaluate the predictive value of early embryo cleavage (25 - 27 hours post insemination/ICSI) of day two 4-cell preembryos which showed a single nucleus in each blastomere (“4-cell / 4 nuclei” preembryo) at the time of transfer. In previous studies, we have demonstrated that transfer of day two 4-cell preembryos with a synchronous appearance of nucleation yields a significantly higher implantation rate compared to transfer of 4-cell preembryos with an asynchronous appearance of nucleation (0 - 3 blastomeres showing a single nucleus). Also early embryo cleavage has been claimed to be an important marker for implantation potential of an embryo. Retrospective study. Single embryo transfers. Early cleaving preembryos, which were “4-cell / 4 nuclei” preembryos at the time of transfer, were primarily chosen for transfer. If no such embryo was available, a “4-cell / 4 nuclei” preembryo which had not cleaved early was taken for transfer. 364 consecutive fresh day two single embryo transfers of “4-cell / 4 nuclei” preembryos were performed from February 2004 to February 2005. Implantation rates (at least a gestational sac at ultrasound examination at 7 weeks of gestation) of “4-cell / 4 nuclei” preembryos which had or had not cleaved early were analysed. The pregnancy/implantation rates after transfer of day two “4-cell / 4 nuclei” preembryos with or without early cleavage are shown in the table. Tabled 1 The observation early embryo cleavage adds no extra in predicting implantation potential of a day two 4-cell preembryo with mononucleate blastomeres.