Oocyte karyotyping by comparative genomic hybrydization provides a highly reliable method for selecting “competent” embryos, markedly improving in vitro fertilization outcome: a multiphase study

Objective

To assess the karyotypic relationship between prefertilized/postfertilized oocytes and embryos using comparative genomic hybridization (CGH) on polar body-1 (PB-1), PB2, and blastomere biopsies and to evaluate IVF outcomes after transfer of blastocysts derived from euploid oocytes.

Design

Prospective cohort.

Setting

Medical center.

Patient(s)

Phase1: Fourteen oocyte donors (23–29 years). Phase 2: Forty-one healthy embryo recipients aged 29–43 years free of endometrial implantation dysfunction. In 30 cases own eggs were used. Eleven women used donated oocytes.

Intervention(s)

Phase 1: PB-1 biopsies followed intracytoplasmic sperm injection (ICSI), PB-2, and day 3 blastomere biopsies. Phase 2: PB-1 biopsy followed by ICSI using normal sperm and the subsequent embryo transfer of ≤2 blastocysts derived from euploid oocytes. Comparative genomic hybridization on all DNA derived from phase 1 and 2 biopsies.

Main Outcome Measure(s)

Pregnancy and implantation rate.

Result(s)

Phase 1: 39% of oocytes and 88% of zygotes were euploid; >95% progressed to blastocysts. Mosaicism as evidenced by euploid oocytes developing into aneuploid zygotes or embryos occurred in 13% of concepti. Phase 2: Six of 30 women using own eggs, who failed to produce euploid oocytes, were cancelled. Thirty-five women underwent embryo transfers with ≤2 (mean, 1.3 ± 0.7) blastocysts derived from euploid oocytes. The ongoing pregnancy/implantation rates per embryo transfer were 74% and 82%, respectively.

Conclusion(s)

Transferring euploid embryos markedly improved IVF outcome. These findings, if corroborated, could initiate a paradigm shift in assisted reproductive technology (ART).

Key Words: Comparative genomic hybridization, karyotype, embryo transfer, pregnancy, implantation