The Effect of Artificial Oocyte Activation on Blastocyst Development in Patients With Low Blastocyst Rates: A...

Physiological oocyte activation requires a synergy between the oocyte and sperm to release calcium (Ca²⁺) through oscillations. The absence of such synergy between the oocyte and sperm leads to a negative impact on oocyte activation. Artificial oocyte activation (AOA) can be performed by mechanical, chemical, or electrical approaches. Studies have shown that AOA is helpful in cases of fertilization failure or low fertilization rate, especially in couples with globozoospermia. However, mixed opinions are present on the effect of AOA on blastocyst rate. Thus, this study aimed to investigate the effect of AOA on blastocyst rate in patients with poor or no blastocyst development on their previous In Vitro Fertilization-Intracytoplasmic Sperm Injection (IVF-ICSI) attempt.

This retrospective cohort single-center study compared intracytoplasmic sperm injection (ICSI) AOA cycles with previous conventional ICSI cycles, and conventional ICSI without AOA cycles with previous conventional ICSI cycles in couples with failed or low blastocyst rates (<30%) in the original ICSI cycle. In total, 54 couples with suboptimal blastocyst development between January 2018 and October 2023 were included in the study. Twenty-two couples underwent an ICSI-AOA cycle consisting of calcium ionophore (GM508-CultActive) exposure on their second cycle, and 32 couples underwent conventional ICSI without an AOA cycle on their second cycle. The primary outcome measured was blastocyst rate, and secondary outcomes were the percentage of patients without usable embryos, oocyte maturation, fertilization, and pregnancy rates.

We compared 22 AOA cycles to previous conventional ICSI cycles in the same patients and 32 conventional ICSI cycles without AOA to previous conventional ICSI cycles in the same patients. After AOA, the blastocyst rate was not significantly higher than the control group (48% versus 29%, p=0.19). Conversely, the blastocyst rate was significantly higher in the conventional ICSI without AOA cycles than in the control group (48% versus 24%, p=0.04). The fertilization rate and the percentage of patients without usable embryos were not statistically significant between the first and second cycles in both groups.

The literature still lacks strong evidence for AOA overcoming impaired embryonic development. Therefore, AOA remains reserved for couples with a failed or low fertilization history to improve fertilization results. Optimal laboratory conditions and ovarian stimulation modifications without AOA may improve blastocyst rates. Further research is needed to validate our findings due to the presence of confounding factors, small sample size, and retrospective design of the study.