This study aimed to compare the impact of ICSI versus traditional IVF insemination on embryo quality in a case of non-male factor and a history of previously cancelled IVF treatment cycles for poor-quality embryo. This study documented that ICSI did not increase fertilization, cleavage embryos, and available embryos rate. Our findings agree with previous studies by Panagiotis et al., who also found mean fertilization rates and embryo utilization rates were comparable between IVF and ICSI in the whole cohort [9]. Taylor TH. et al. concluded that the more immature oocytes undergo a complete maturation during IVF, the higher the likelihood to fertilize spermatozoa in an incubator overnight [10]. However, in this study, the absolute MII oocytes and normal fertilization have no significant difference. There are two possible explanations for this phenomenon. Firstly, the experience of the doctor who monitored the COH protocol plays a critical role. Secondly, in vitro mature had low maturation rates and limited developmental competence, the clinical outcome is still suboptimal [11]. It is well-known that ICSI is related to potential mechanical damage to the oocyte membrane and cytoplasm during the procedure, which can reduce the number of mature oocytes for fertilization. Additionally, it can also result in lower fertilization. However, ICSI could increase the normal fertilization rates with one sperm injection and lower the multiple pronuclear rates in young or advanced age women. The two reasons above caused a similar fertilization rate. The results were consistent with the previous meta-analysis of the effect of ICSI in infertility couples with non-male factor [12] Admittedly, the insemination technique did not affect the normal fertilization rate and available embryo rate. However, the ICSI group had a significantly higher percentage of high-quality embryos compared to the IVF group. Similarly, Farhi, J. et al. studied ICSI in the older IVF population to increase both the fertilization rate and the number of high-quality embryos [13]. Yang et al. also found a similar fertilization rate in the IVF and ICSI groups. However, embryo quality and clinical outcomes were higher after ICSI [14]. The superiority of ICSI is the result of the ICSI procedure avoiding oocyte and zygote culture. It involved a lot of spermatozoa and reduced exposure to the reactive oxygen species, which was produced by spermatozoa. Besides, modified ICSI techniques can trigger artificial calcium (Ca2+), which plays a critical role in embryo cleavage and development [15, 16]. Whereas, in contrast to our findings, May-Tal et al. demonstrated a higher-quality blastocyst rate in the IVF group than the ICSI group [6]. This finding also failed to draw consistently with the previous meta-analysis based on four cohort studies [12]. These differences are explainable through the different patients involved, sample sizes, statistical methods, and research design. Furthermore, Blake M et al. revealed that the location of the injection impacted the embryo quality, with injection near the meiotic spindle causing a lower day 3 embryo quality [17]. Moreover, the competence of the embryologist could be another factor that affects the success rates of ICSI. Therefore, in our centre, ICSI was performed by two experienced embryologists. The confusing question was that the ICSI group can’t receive additionally available embryos in this study. Maybe for the intrinsic factor of gametes. Since this study involved a group of patients who had a normal ovarian response, non-male infertility factor without available embryo after normal fertilization, the special group of patients with poor-quality embryo most got it by the intrinsic factor of gametes. Yoeli et al. suggested that embryo quality depends on the intrinsic factor of the gametes, such as oocyte cytoplasmic factors, maternal-effect mutations, and sperm DNA fragments, rather than on the fertilization process per se., may explain [18]. Nevertheless, our findings do not agree with Yoeli et al. considered embryo quality does not seem to be influenced by the mode of fertilization. The study included patients who retrieved oocytes up to 20, it’s ovarian hyper-responsiveness. Labarta, E. et al. demonstrate that using gonadotrophin doses was related to embryo quality [19]. It is well known that an improper gonadotrophin dose can lead to ovarian hyper-responsiveness.
For the clinical outcome of the two groups, the significant higher cumulative clinical pregnancy rate, mainly because embryo quality is a major factor that determines the chances of pregnancy in the context of assisted reproductive technologies (ART). We believe that, through expend the study sample, the cumulative implantation rate will have a statistically significant difference.
Therefore, the current data was limited by the retrospective study and the potential of bias due to unmeasured confounders. Furthermore, the choice between IVF and ICSI was somehow arbitrary and focused on a specific period. Moreover, the sample size was limited by the small number of suitable patients. However, the present study was the first to investigate the laboratory treatment strategies for the subpopulation who had their previous IVF cycle cancelled for poor-quality embryo, and the results of our study strongly suggest that ICSI can improve the embryo quality.
In conclusion, for ovarian response normal, got normal fertilization after the conventional method, and for poor-quality embryos in previous IVF cycle patients, ICSI may provide an advantage over IVF. Admittedly, it does not increase the fertilization rates and available embryo rate. However, it can increase high-quality embryo rates and clinical pregnancy. Further large prospective studies are needed to elucidate the aforementioned recommendation before its routine implementation.