Effects of assisted oocyte activation with calcium- ionophore and strontium chloride on in vitro ICSI outcomes

Objective(s): Failed fertilization after intra-cytoplasmic sperm injection (ICSI) is mainly attributed to failed oocyte activation and can be overcome by artificial oocyte activation (AOA). The present study aims to compare in vitro outcomes of ICSI following two different assisted oocyte activation chemical procedures (SrCl2 and Ionomycin) in sibling oocytes of ICSI candidates. Materials and Methods: From March 2015 until February 2016, 105 infertile men with 99-100% abnormal sperm morphology, irrespective of sperm motility, concentration, or origin (semen or testicular) were included in this study. Out of these, 66 couples accepted to be included in the study group (Ionomycin/SrCl2) and 39 couples requested routine AOA procedure (Ionomycin) as external control group. Primary outcomes of this study (fertilization, embryo quality, and post-implantation development) were compared between these groups. Results: Significantly higher oocyte activation (67.90 +/- 3.6% vs. 51.16 +/- 3.6%, P=0.004) and fertilization (65.23 +/- 3.63% vs. 49.65 +/- 3.63%, P=0.008) rates were observed in sibling oocytes treated with Ionomycin in comparison to the SrCl2 sibling group. Percentage of top quality embryos was insignificantly higher in SrCl2 groups compared to the Ionomycin group (29.90 +/- 4.27 vs. 20.65 +/- 4.05%, P=0.26). Conclusion: Ionomycin may be superior to SrCl2 for inducing oocyte activation. However, SrCl2 may be a more efficient means to support the development of better quality embryos following ICSI.