Validation of the Fertilization Stage in IVF Cycles- Is It Really Necessary?

Introduction

The standard embryological work-up in the IVF laboratory involves checking each oocyte on the day after ovum pick-up (OPU) for the presence of two pronuclei post-insemination - indicating fertilization. Some IVF units are not active on one day of the weekend; therefore, normal fertilization cannot be validated.

Aim

To check whether cycles in which validation of fertilization did not take place during the weekend have lower pregnancy rates as compared to normal weekday cycles.

Materials & Methods

This retrospective case-control study included 446 OPU/ICSI cycles at Shaare Zedek Medical Center from 2013 to 2014. The outcome of OPU cycles performed on Fridays, in which fertilization could not be validated, were compared to that of cycles performed on regular weekdays. We thereafter looked at the embryological outcome and pregnancy rates of embryos that were derived from cycles in which fertilization was checked but could not be observed. The latter were used as test-cases to elucidate the importance of validation of fertilization.

Results

No statistically significant difference was found in clinical pregnancy rates between the two groups: Friday-cycles (31.3%) versus weekday-cycles (33.3%).

Moreover, despite routine embryological workup during weekdays, 25.9% of these cycles included oocytes in which validation of fertilization could not be observed. The outcome of this group of embryos will be further discussed.

Conclusion

In an IVF+ICSI program that is not active for one day per week, omitting the validation of the fertilization step did not affect pregnancy rates.