Comparison of embryo development in sibling oocytes cultured in two different sequential media

Objective: To compare the efficiency of two different sequential media for the cultivation of sibling embryos until the blastocyst stage. Design: A prospective analysis was conducted on 113 ART cycles with the indication of severe male factor infertility in Istanbul Memorial Hospital ART and Genetics Unit. Setting: After insemination, oocytes were randomly divided into two groups and cultured with either ISM1/ISM2 or G1.2/G2.2 sequential media until embryo transfer. Embryo development parameters were recorded for every embryo on consecutive days of preimplantation embryo development, growing in each set of culture media. Results: 16.7±6.4 MII oocytes were retrieved. Out of 1434 MII oocytes injected, 1044 were fertilized (72.8%). There was no statistically significant difference in the rate of fertilization (p>0.05). Also, there was no difference in embryo development on the second day of cultivation. On the 3rd day of cultivation, the mean number of blastomeres was significantly higher in embryos cultivated within ISM1 (p<0.01). There was no statistically significant difference among the two groups in terms of blastulation rate. Discussion: Both G1.2-G2.2 and ISM1-ISM2 sequential cultures are equally effective for in-vitro cultivation of embryos until the blastocyst stage. Our results show that both commercial media can be used as valuable and efficient alternatives to each other for sustaining blastocyst development in extended embryo culture programs. ISM1 may be preferred when blastomere biopsy for preimplantation genetic diagnosis is planned as more embryos with 7-8 blastomeres can be available with the use of ISM1.