Comparison of two different oocyte vitrification methods: a prospective, paired study on the same genetic background and stimulation protocol.

Study Question: Can two different methods for oocyte vitrification, one using an open tool and the other a closed tool, result in similar oocyte survival rates?

Summary Answer: The oocyte survival rate was found to be higher in the closed method.

What Is Known Already: Open vitrification is performed routinely in oocyte donation cycles. Closed oocyte vitrification may result in slower cooling rates and thus it is less used, even though it has been recommended in order to avoid the risk of cross-contamination between material from different patients.

Is there a relation between the time to ICSI and the reproductive outcomes?

Study Question: Does time to ICSI affect reproductive outcomes?

Summary Answer: Biochemical and clinical pregnancy diminish progressively as time between oocyte pick up (OPU) and ICSI increases after fresh embryo transfer.

What Is Known Already: Appropriate oocyte cytoplasmic and nuclear maturation are of paramount importance to ensure an optimal embryonic developmental competence. While nuclear maturation is usually attained by the time an oocyte reaches OPU, cytoplasmic maturation cannot be readily assessed and might be incomplete.

Oocyte vitrification does not affect early developmental timings after intracytoplasmic sperm injection for women younger than 30 years old.

Oocyte vitrification causes a temporary disassembly of the metaphase plate and spindle, which needs time to recover after warming. As a consequence, early post-fertilization events-such as timing of second polar body extrusion-might be altered, with unknown effects on preimplantation development, timing to pronuclear breakdown, and timing of cleavages. The aim of this study was to evaluate if differences exist among these events when comparing embryos obtained from fresh-donated versus vitrified/warmed oocytes from young women.

Should we worry about the clock? Relationship between time to ICSI and reproductive outcomes in cycles with fresh and vitrified oocytes.

Study Question: Is there an optimal time to perform ICSI with respect to the times of oocyte pick-up (OPU), in order to maximize the reproductive outcomes in cycles with fresh and vitrified/warmed donor oocytes?

Summary Answer: We found no significant differences in reproductive outcomes of ICSI cycles within a wide range of times between OPU and ICSI.

What Is Known Already: In assisted reproduction, the oocyte is subject to denudation, vitrification/warming and ICSI. As shorter interaction with cumulus cells, oocyte ageing in vitro and insufficient recovery after warming may all impact the resulting embryo developmental competence, strictly controlled times between procedures are often implemented.