Efficiency and efficacy of vitrification in 35 654 sibling oocytes from donation cycles

STUDY QUESTION

Is oocyte vitrification/warming as efficient and effective as using fresh oocytes in donation cycles?

SUMMARY ANSWER

IVF with vitrified donor oocytes is less efficient than using fresh oocytes, but its efficacy remains comparable to that of fresh cycles.

WHAT IS KNOWN ALREADY

Oocyte vitrification is used to preserve the reproductive potential of oocytes. A small number of randomized controlled trials carried out by experienced groups have shown that this technique provides fertilization, pregnancy, implantation and ongoing pregnancy rates comparable to those of fresh oocytes. However, large registry-based analyses have consistently reported lower live birth rates (LBRs) in cycles using vitrified oocytes. It is not clear whether this decrease may be due to the effect of vitrification per se on the oocytes or to the lower efficiency of the technique, as some of the oocytes do not survive after warming.

STUDY DESIGN, SIZE, DURATION

Retrospective cohort analysis of 1844 cycles of oocyte donation (37 520 oocytes), each donor in the study provided enough oocytes for at least one reception cycle with fresh oocytes (2561 cycles) and one reception cycle with vitrified oocytes (2471 cycles) from the same ovarian stimulation (sibling oocytes). Overall, 35 654 oocytes were considered in the analysis. All embryo transfers (n = 5032) were carried out between 2011 and 2017.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Differences in reproductive outcomes after the first embryo transfer were evaluated using Pearson's Chi-squared test and regression analysis adjusted for recipient's age, BMI, sperm origin and state, day of embryo transfer, morphological score and number of transferred embryos. We performed two additional sub-analyses, to test whether the efficiency and/or effectiveness of vitrification/warming impacts reproductive results. One analysis included paired cycles where the same number of fresh and vitrified oocytes were available for ICSI (SAME sub-analysis), while the second analysis included those cycles with a 100% survival rate post-warming (SAME100 sub-analysis).

MAIN RESULTS AND THE ROLE OF CHANCE

Baseline and cycle characteristics of participants were comparable between groups. Overall, fertilization rates and embryo morphological scores were significantly lower (P < 0.001) when using vitrified oocytes; moreover, vitrified oocytes also resulted in lower reproductive outcomes than sibling fresh oocytes using both unadjusted and adjusted analyses: ongoing pregnancy (32.1% versus 37.5%; P < 0.001; OR 0.88, 95% CI 0.77, 1.00) and live birth (32.1% versus 31.9%; P = 0.92; OR 1.16, 95% CI 0.90, 1.49). However, when the efficiency of warming was taken into account, reproductive outcomes in recipients became comparable: ongoing pregnancy (33.5% versus 34.1%; P = 0.82; OR 1.11, 95% CI 0.87, 1.43) and LBR (32.1% versus 32%; P = 0.97; OR 1.15, 95% CI 0.89, 1.48). Moreover, after selecting only cycles that, in addition to having the same number of oocytes available for ICSI, also had 100% post-warming survival rate in the vitrified group, reproductive outcomes were also comparable between fresh and vitrified oocytes: ongoing pregnancy (34.8% versus 32.4%; P = 0.42; OR 1.32, 95% CI 0.98, 1.77) and live birth (32.9% versus 31.0%; P = 0.52; OR 1.27, 95% CI 0.95, 1.71), indicating that reproductive outcomes of these cycles are affected by the efficiency of the vitrification/warming technique performed rather than the oocyte damage due to the fast cooling process to which oocytes are subjected.

LIMITATIONS, REASONS FOR CAUTION

An open vitrification system was used for all cases, and oocyte vitrification/warming was performed by experienced embryologists with consistently high survival rates; caution must be exerted when extrapolating our results to data obtained using other open vitrification systems, closed vitrification systems or to IVF units with survival rates <90%.

WIDER IMPLICATIONS OF THE FINDINGS

This is the largest cohort study comparing reproductive outcomes of vitrified and fresh sibling donor oocytes to date. We found that, when the number of oocytes available after warming is equal to the number of fresh oocytes, reproductive results including live birth are comparable. Consequently, the efficiency of vitrification must be taken into account to achieve the same reproductive outcomes as with fresh oocytes. We recommend implementing strict indicators of vitrification/warming efficiency in clinics and refining vitrification/warming protocols to maximize survival.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by intramural funding of Clínica EUGIN and by the Secretary for Universities and Research of the Ministry of Economy and Knowledge of the Government of Catalonia (GENCAT 2015 DI 048). The authors declare no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

Is increasing paternal age negatively associated with donor oocyte recipient success? A paired analysis using sibling oocytes

OBJECTIVE

To determine if increasing paternal age has an adverse effect on pregnancy outcomes in paired donor egg recipients who received oocytes from the same donor in the same stimulation cycle.

DESIGN

Retrospective cohort study.

SETTING

Reproductive Medicine Center.

PATIENT(S)

The study included 154 recipients who received oocytes from a split donor oocyte cycle and received sperm from men in discrepant age groups (group A: <45 years old; group B: ≥45 years old).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Implantation rate, pregnancy loss rate, pregnancy rate, and live birth rate.

RESULT(S)

The median paternal age was 41 years old for group A and 48 years old for group B. The pregnancy rate was 81% in group A compared with 69% in group B. The live birth rate was 65% in group A compared with 53% in group B. The rate of pregnancy loss was 19% in group A and 23% in group B. The implantation rate was 69% in group A compared with 66% in group B. The adjusted odds of pregnancy were found to be 65% lower for patients in the older partner age group (95% confidence interval [CI], 0.13, 0.95). The adjusted odds of live birth rate (odds ratio [OR], 0.45; 95% CI, 0.20, 1.00), implantation rate (OR, 0.91; 95% CI, 0.43, 1.92), and rate of pregnancy loss (OR, 1.5; 95% CI, 0.5, 4.5) favored the younger partner age group; however, these results were not statistically significant.

CONCLUSION(S)

In this model that controlled for oocyte quality to the greatest degree possible by using paired recipients from the same donor from the same stimulation cycle, we found that increased paternal age had a negative effect on pregnancy rates.

physiological selection of spermatozoa for ICSI (picsi) in sibling oocytes

BACKGROUND

Physiological selection of spermatozoa for ICSI (PICSI) is a sperm selection method based on sperm binding to hyaluronic acid. Previous studies on the effect of hyaluronic acid binding assays on fertilization and embryo quality have shown inconsistent results. Previous sibling oocyte studies have not found a significant improvement in fertilization or embryo development with hyaluronic acid binding assays.

OBJECTIVE

To compare fertilization and embryo development between standard intracytoplasmic sperm injection (ICSI) and PICSI in sibling oocytes.

MATERIALS AND METHODS

This is a retrospective analysis of all in vitro fertilization (IVF) cycles between January 2017 and April 2020 in which sibling oocytes were randomly fertilized by both ICSI and PICSI. Fertilization rate and the rate of embryos eligible for transfer were compared.

RESULTS

Forty-five IVF cycles, in which 257 oocytes were fertilized with PICSI and 294 with standard ICSI, were compared. Most of the patients included in the study had previous failures of fertilization, poor embryonic development, implantation failure, or miscarriage. All but two of the patients had at least one previous unsuccessful IVF cycle. Both fertilization rates (71% vs. 83%) and transfer eligible embryo rates (38% vs. 51%) were significantly higher in PICSI fertilized oocytes (p = 0.008 and p = 0.01 respectively).

DISCUSSION

Our study is the largest sibling oocyte study comparing ICSI and PICSI, and the first to find a significant improvement in fertilization and embryo quality with PICSI using sibling oocytes. The fact our cohort included almost exclusively couples with previous unsuccessful IVF cycles might suggest that PICSI should be used in selected cases.

CONCLUSION

PICSI improves fertilization rates and transfer eligible embryo rates in sibling oocytes in a selected study group.

The Presence of Endometrioma Does Not Impair Time-Lapse Morphokinetic Parameters and Quality of Embryos: A Study On Sibling Oocytes

OBJECTIVE

To see whether the oocytes retrieved from an ovary with an endometrioma would develop into embryos with aberrant timings of cleavage as assessed using time-lapse monitoring (TLM) and poorer morphologic quality compared with sibling oocytes from the contralateral ovary with no endometrioma in the same patient after intracytoplasmic sperm injection.

METHODS

This was an observational prospective study at an in vitro fertilization (IVF) center of a private hospital. It included analysis and comparison of 128 embryos (69 embryos developed from the ovary with endometrioma and 59 embryos from the contralateral ovary without endometrioma serving as controls from a total of 20 women with infertility). Morphology of the embryo was assessed twice (days 3 and 5), again by capturing images with the TLM system. Morphokinetic parameters of embryos and clinical pregnancy rates were recorded separately from ovaries with and without endometrioma and were the primary outcomes of the study. Secondary outcomes included number of retrieved oocytes, number of metaphase II (MII) oocytes, fertilization rates, and conventional morphological classification of embryos.

RESULTS

There were no differences in terms of the following time-lapse morphokinetic parameters of embryos. The mean numbers of oocytes and MII oocytes collected from the ovary with the endometrioma were similar to those collected from the contralateral ovary without endometrioma. Fertilization rates and the percentage of embryos with top morphologic quality were also similar.

CONCLUSIONS

According to the morphokinetic parameters, this study further strengthens the notion that removal of endometriomas before IVF is not a necessity in terms of better oocyte quality and development.

Two different concentrations of oxygen for culturing precompaction stage embryos on human embryo development competence: a prospective randomized sibling-oocyte study

The study was to investigate the effects of oxygen concentration at different levels for culturing pre-compaction embryos on human embryo development competence. A total of 1254 oocytes from 92 patients treated with conventional in vitro fertilization (IVF) were harvested in this study. Oocytes were randomly assigned to the atmospheric (~20%) or low (~5%) oxygen concentration groups on the retrieval day (day 0). Groups were compared with respect to fertilization rates, embryo development, and reproductive outcome. We failed to detect a significant difference on fertilization rate between two groups. However, the low oxygen group yielded more optimal embryos on day 3 when compared with the atmospheric group (72.4% vs. 64.2%). The low oxygen group had a significantly higher blastocyst formation rate than the atmospheric oxygen group (64.5% vs. 52.9%). It is seemly that the optimal blastocyst and frozen blastocyst rates was higher in the low oxygen group, but the data did not reach a statistical significance. Although the use of low oxygen will not affect the clinical outcome in the fresh cleavage-transfer cycles, but it will result in more favorable clinical outcomes in the subsequent warming blastocyst-transfer cycles, with statistically significantly higher clinical pregnancy rate (CPR) and implantation rate (IR) compared with atmospheric oxygen. In conclusion, a low oxygen concentration may significantly improve the developmental potential of pre-compaction embryos, thus resulting in a positive effect on subsequent blastocyst cultivation and optimizing the treatment cycle.

Acrosome index is not an absolute predictor of the outcome following conventional in vitro fertilization and intracytoplasmic sperm injection

PURPOSE

To investigate if including evaluation of acrosome index (AI) in the semen analysis of teratozoospermic samples could help to predict for which patients intracytoplasmic sperm injection (ICSI) is necessary.

METHODS

The fertilization rate, pregnancy rate, and percentage of good quality embryos were compared after performing conventional in vitro fertilization (IVF) and ICSI, respectively, using sibling oocytes. The role of AI was evaluated by dividing patients into two groups; Group A (AI < 7%) and Group B (AI > or = 7%).

RESULTS

A significant difference in fertilization rate was observed between Group A and B after conventional IVF. In Group A, the fertilization rate, embryo transfer rate, and percentage of good quality embryos were higher after ICSI than after IVF. In Group B, the fertilization and pregnancy rates were numerically but not significantly higher after IVF compared to ICSI.

CONCLUSION

Evaluation of acrosome index will not accurately predict fertilization, although this study shows that a sperm sample with less than 5% normal forms and an AI greater than 7% may achieve a mean fertilization rate > 70% after conventional IVF.

The status of controlled prospective clinical trials for efficacy of intracytoplasmic sperm injection in in vitro fertilization for non-male factor infertility

PURPOSE

Intracytoplasmic sperm injection (ICSI) of some sibling oocytes may have a beneficial effect in couples going through in vitro fertilization for causes of infertility not related to the male factor. Our purpose was to critically appraise the randomized controlled studies done in this area and arrive at some recommendations.

METHODS

The four controlled trials done so far have utilized similar methodology, i.e., they randomly allotted sibling oocytes to ICSI versus standard insemination in patients going through in vitro fertilization and embryo transfer.

RESULTS

In the first trial reported in 1995 there was no difference in fertilization rate, whereas the later trials reported in 1997, 1999, and 2000 showed improvement with ICSI that reached statistically significant level in the last two studies.

CONCLUSIONS

Total fertilization failure of an in vitro fertilization cycle can be prevented and fertilization can be improved if half of sibling oocytes are subjected to ICSI.