Blastocyst Biopsy is Preferable to Cleavage Stage Biopsy in IVF-PGD Cycles

Introduction
During the last two years we have been performing day 3 and day 5 IVF-PGD/PGS cycles. Due to the higher success rates in day-5 biopsies and the worldwide trend, we present this study comparing the outcome between day-3 and day-5/6 IVF-PGD cycles.

Aim
To compare the outcome rate between day-3 and day-5/6 IVF-PGD cycles.

Materials and Methods
From January 2016 until August 2017, total of 100 IVF/ICSI-PGD cycles were performed. In 28 day-3 PGD cycles, a single blastomere was biopsied using Ca/Mg free medium. In 72 day-5/6 PGD cycles, zona drilling was performed on day 3 followed by trophoectoderm biopsy from hatching day 5/6 blastocysts, using laser and mechanical separation, in MHM medium. Biopsies were analyzed by PCR. All blastocysts were vitrified on the biopsy day.

Results
Our results show higher success rates in day-5/6 IVF-blastocyst-PGD cycles as compared to IVF day-3-PGD cycles. In day-5/6 and day 3-PGD cycles, 276 and 173, embryos were analyzed, respectively, 60 and 24 embryo transfers were performed with transfer of a total of 73 and 38 embryos, respectively. Clinical pregnancy rates were 43.3% vs 25.0% (NS) and implantation rates were 38.4% vs 18.4% (p<0.05), respectively.

Conclusions
Biopsy of blastocysts, more than doubles the implantation rate as compared to day-3 biopsies, similar to the worldwide accumulating data, that blastocyst biopsy is preferable to day-3 biopsy. We propose that sampling a selected group of embryos (blastocysts), and aspirating smaller proportion of the embryo, enable the achievement of higher outcome rates.