Author(s): Fancsovits P, Toth L, Takacs ZF, Murber A, Papp Z,
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Abstract OBJECTIVE: To examine whether the timing of pronuclear breakdown can be a predictor of embryo quality and viability. DESIGN: Retrospective comparison of the development and quality of early and late developing zygotes. SETTING: Infertility and endocrinology unit in a university hospital. PATIENT(S): One thousand seven hundred eighty-two zygotes obtained in 383 consecutive IVF cycles. INTERVENTION(S): Culture of all fertilized embryos. MAIN OUTCOME MEASURE(S): Number of fertilized zygotes showing early pronuclear breakdown at 22-25 hours postinsemination, embryo quality, pregnancy rates (PR), implantation rates. RESULT(S): Early pronuclear breakdown embryos had a significantly higher cell number (4.4 +/- 1.2) compared with the late pronuclear breakdown embryos (3.6 +/- 1.4). When comparing the frequency of the early pronuclear breakdown embryos according to the method of fertilization, we failed to find any significant difference between the IVF (37.1\%) and the intracytoplasmic sperm injection (ICSI) (41.1\%) groups. The transfer of early pronuclear breakdown embryos resulted in a significantly higher clinical pregnancy rate than those with late pronuclear breakdown (48.3\% vs. 27.3\%). The implantation rate was higher in the early pronuclear breakdown group than in the late pronuclear breakdown group (26.5\% vs. 15.1\%). CONCLUSION(S): Early pronuclear breakdown is a strong indicator of embryo viability, and may be used as an additional criterion in the selection of embryos for transfer.
This article was published in Fertil Steril
and referenced in Journal of Fertilization: In Vitro - IVF-Worldwide, Reproductive Medicine, Genetics & Stem Cell Biology