Embryo morphokinetics analysis and reproductive outcomes with assisted oocyte activation by a calcium ionophore after prior fertilization failure. A multicentric retrospective study

Background

Fertilization failure or low fertilization rate after ICSI is around 1–3% in IVF treatments. Several strategies have been studied in order to bypass the lack of activation. The aim of this study is to evaluate embryo morphokinetics and reproductive outcomes after intracytoplasmic sperm injection (ICSI) with assisted oocyte activation (AOA) using a calcium ionophore (CaI) in patients with previous fertilization failure or low fertilization rate (under 30%) and severe male factor.

Methods

Multicentric retrospective cohort study including 70 patients with fertilization failure or low fertilization rate and severe male factor (sperm concentration under 1 million/mL) who underwent ICSI with CaI (756 oocytes), and 76 patients with severe male factor without previous fertilization failure who had standard ICSI (748 oocytes) between January 2011 and December 2016.

Results

CaI Exposed and non-exposed groups differed significantly for normal fertilization rates, pronuclear disappearance timing (tPNf), time to 4 cells stage, multinucleation at the 2- and 4-cell stages, and direct cleavage events. Implantation rate was higher in the non-exposed group (p = 0.023). Other morphokinetic variables were similar between groups. Pregnancy (higher in the non exposed group), abortion, and live birth rates, were also not statistically different among groups.

Conclusions

Although the fertilization and implantation rates were higher in the non-exposed group, ICSI-CaI was associated with an increased fertilization rate compared to patient previous attempts and thus with increased pregnancy chances. Because of the specific patient populations involved (patients with severe male factor with or without previous fertilization failure), the results might not generalize for patients with different etiologies.

Trial Registration: 1506-VLC-045-MM.