Cleavage Stage versus Blastocyst Stage Embryo Transfer in Oocyte Donation Cycles.

BACKGROUND AND OBJECTIVE: During the last few years, a trend has been noted towards embryos being transferred at the blastocyst stage, which has been associated with improved rates regarding implantation and clinical pregnancy in comparison to cleavage stage embryo transfers. There is a limited number of studies investigating this notion in oocyte donation cycles employing cryopreserved embryos. The aim of this study is to evaluate the implantation potential and clinical pregnancy rates between the day 3 cleavage stage and blastocyst stage embryo transfers in oocyte donation cycles employing vitrified embryos. METHODS: This is a retrospective evaluation of oocyte donation frozen-thawed transfers completed in our clinic from January 2017 to December 2017. Intracytoplasmic sperm injection was conducted for all oocytes. Following fertilization, all embryos were cryopreserved either at the cleavage or blastocyst stage. Embryo transfer of two embryos was performed under direct sonographic guidance in all cases. Results: Our results confirmed a 55.6% clinical pregnancy (CP) resulting from day 3 embryo transfers, a 68.8% CP from day 5, and 71.4% CP from day 6. Significantly improved pregnancy rates were related to embryo transfers at the blastocyst stage when compared to cleavage stage transfers (68.9% and 55.6% respectively, p = 0.016). The risk with regards to multiple pregnancies was similar. CONCLUSION: Our findings indicate that in oocyte donation cycles employing vitrified embryos, embryo transfer at the blastocyst stage is accompanied with a significant improvement in pregnancy rates and merits further investigation.

The Effect of Open and Closed Oocyte Vitrification Systems on Embryo Development: A Systematic Review and Network Meta-Analysis.

Background/Objectives: Open and closed vitrification systems are commonly employed in oocyte cryopreservation; however, there is limited evidence regarding a comparison of their separate impact on oocyte competence. This study uniquely brings to the literature, data on the effect of open versus closed vitrification systems on laboratory and clinical outcomes, and the effect of cooling and warming rates. Methods: A systematic search of the literature was performed using the databases PubMed/MEDLINE and the Cochrane Central Library, limited to articles published in English up to January 2023. A network meta-analysis was conducted comparing each vitrification system versus fresh oocytes. Results: Twenty-three studies were included. When compared to fresh oocytes, both vitrification devices resulted in lower fertilization rates per MII oocyte retrieved. When comparing the two systems in terms of survival rates, no statistically significant difference was observed. However, interestingly open systems resulted in lower cleavage and blastocyst formation rates per 2 pronuclear (2PN) oocyte compared to fresh controls, while at the same time no statistically significant difference was detected when comparing closed devices with fresh oocytes. Conclusions: In conclusion, closed vitrification systems appear to exert a less detrimental impact on the oocytes' competence, which is reflected in the blastocyst formation rates. Proof of superiority of one system versus the other may lead to standardization, helping to ultimately determine optimal practice in oocyte vitrification.

Laser versus mechanical assisted hatching: a prospective study of clinical outcomes.

OBJECTIVE: To compare clinical outcomes after laser or mechanical techniques of assisted hatching (AH) in women of advanced age undergoing IVF or intracytoplasmic sperm injection (ICSI). DESIGN: Prospective randomized study. SETTING: Center for Human Reproduction, Genesis Clinic, Athens, Greece. PATIENTS: Three hundred and sixteen consenting women of advanced age (> or =39 years) with primary infertility undergoing IVF/ICSI programs and having available embryos for transfer on day 3. Patients were randomized into laser or mechanical AH of their transferred embryos. INTERVENTIONS: Controlled ovarian hyperstimulation, oocyte retrieval, IVF/ICSI, laser or mechanical AH, and embryo-transfer. MAIN OUTCOME MEASURES: Implantation rate, clinical pregnancy rate, and viable pregnancy rate. RESULTS: The implantation rate was significantly higher in the laser AH group. Clinical and viable pregnancy rates were higher (but not significantly) in the laser AH group. CONCLUSIONS: Laser AH of embryos may result in better clinical outcomes when compared to the mechanical technique in women of advanced age undergoing IVF or ICSI.