Objective

With further improvements in the embryo culture systems it will become possible in the near future to achieve high implantation rates even with single blastocyst transfers. Enzymatic treatment of the zona pellucida seems that it does not alter the pregnancy and implantation rates, but further studies with larger group of patients are needed to clarify the real effect of this zona manipulation on pregnancy outcome.

Selective fertilization of one oocyte from a binovular zona pellucida by ICSI may lead to the development of a morphologically normal blastocyst-stage embryo which can be used for embryo transfer in the presence of a limited number of embryos.