Evaluation of the quality of embryo based on morphology cultured at low oxygen concentration

Abstract

Objectives: evaluating the quality of embryo morphology cultured at low oxygen concentration (5%) at different stages of embryonic development: day 3, day 5. Methods: the present study examined 168 IVF/ICSI cycles from October 2019 to February 2021 at the Assisted Reproductive Center, 16A Ha Dong General Hospital. Embryos were randomly assigned to 2 groups: group 1 used a K-system G-210 tri-gas incubator (Australia) (5% O2, 5% CO2, 90% N2) while group 2 used a Thermo Scientific 371 dual-gas incubator (Denmark) (5% CO2, 75% N 2 with 20% atmospheric Oxygen concentration). Participants in the study were patients younger than 37 years old, with AMH>1.2 ng/ml, and AFC≥4. Mature oocytes were injected with sperm, and cultured in a sequential medium (G1,G2-PLUSTM). Embryologists assessed embryos on the day of fertilisation, days 3, 5, and compared the results of the two groups, using the method of descriptive statistics and T-test. The results revealed an insignificant difference in fertilisation rate and the quality of cleavages cultured in these 2 groups (percentages of good- and average quality cleavages were, in turn, 77.28±4.62% và 77.99±5.03%, at p>0.05, number of poor quality cleavages were, in turn, 1.71±0.38 vs 1.97±0.49 with p>0.05). The results on day 5 embryo showed that the percentage of blastocysts (from fertilisation) and the percentage of morphologically good- and average-quality blastocysts tended to increase higher when cultured in 5% oxygen concentration (p<0.05) compared with the 20% one (57.79±3.60% and 53.05±4.50%, 78.62±4.42% and 70.97±5.67%, respectively). Conclusions: embryo cultured in a low oxygen concentration helps embryos develop better on day 5 than when cultured at atmospheric concentrations.