Transfer of frozen-thawed blastocysts that underwent quarter laser-assisted hatching at the day 3 cleaving stage before freezing

Developmental potential of surplus morulas with delayed and/or incomplete compaction after freezing-thawing procedures

BACKGROUND

Morulas with delayed growth sometimes coexist with blastocysts. There is still limited evidence regarding the optimal disposal of surplus morulas. With the advancement of vitrification, the freezing-thawing technique has been widely applied to zygotes with 2 pronuclei, as well as embryos at the cleavage and blastocyst stages. The freezing of morulas, however, has rarely been discussed. The purpose of this study was to investigate whether these poor-quality and slow-growing morulas are worthy of cryopreservation.

METHODS

This is a retrospective, observational, proof-of-concept study. A total of 1033 day 5/6 surplus morulas were cryopreserved from January 2015 to December 2018. The study included 167 women undergoing 180 frozen embryo transfer cycles. After the morulas underwent freezing-thawing procedures, their development was monitored for an additional day. The primary outcome was the blastocyst formation rate. Secondary outcomes were clinical pregnancy rate, live birth rate and abortion rate.

RESULTS

A total of 347 surplus morulas were thawed. All studied morulas showed delayed compaction (day 5, n = 329; day 6, n = 18) and were graded as having low (M1, n = 54), medium (M2, n = 138) or high (M3, n = 155) fragmentation. The post-thaw survival rate was 79.3%. After 1 day in extended culture, the blastocyst formation rate was 66.6%, and the top-quality blastocyst formation rate was 23.6%. The day 5 morulas graded as M1, M2, and M3 had blastocyst formation rates of 88.9, 74.0, and 52.8% (p < 0.001), respectively, and the top-quality blastocyst formation rates were 64.8, 25.2, and 9.0% (p < 0.001), respectively. The clinical pregnancy rate was 33.6%.

CONCLUSIONS

The post-thaw blastocyst formation rate was satisfactory, with approximately one-half of heavily fragmented morulas (M3) developing into blastocysts. Most of the poor-quality morulas were worth to freeze, with the reasonable goal of obtaining pregnancy and live birth. This alternative strategy may be a feasible approach for coping with poor-quality surplus morulas in non-PGS (preimplantation genetic screening) cycles.

Blocking connexin channels improves embryo development of vitrified bovine blastocysts

Connexins (Cxs) are required for normal embryo development and implantation. They form gap junctions (GJs) connecting the cytoplasm of adjacent cells and hemichannels (HCs), which are normally closed but open in response to stress conditions. Excessive HC opening is detrimental for cell function and may lead to cell death. We found that hatching of in vitro-produced bovine embryos, matured in serum-containing conditions, was significantly improved when vitrification/warming was done in the presence of Gap26 that targets GJA1 (Cx43) and GJA4 (Cx37). Further work showed that HCs from blastocysts produced after oocyte maturation in the presence of serum were open shortly after vitrification/warming, and this was prevented by Gap26. Gap26, applied for the exposure times used, inhibited Cx43 and Cx37 HCs while it did not have an effect on GJs. Interestingly, Gap26 had no effect on blastocyst degeneration or cell death. We conclude that blocking HCs protects embryos during vitrification and warming by a functional effect not linked to cell death.

A retrospective study of single frozen-thawed blastocyst transfer

OBJECTIVE

To study the clinical outcomes of single frozen-thawed blastocyst transfer cycles according to the hatching status of frozen-thawed blastocysts.

METHODS

Frozen-thawed blastocysts were divided into three groups according to their hatching status as follows: less-than-expanded blastocyst (≤EdB), hatching blastocyst (HgB), and hatched blastocyst (HdB). The female age and infertility factors of each group were evaluated. The quality of the single frozen-thawed blastocyst was also graded as grade A, tightly packed inner cell mass (ICM) and many cells organized in the trophectoderm epithelium (TE); grade B, several and loose ICM and TE; and grade C, very few ICM and a few cells in the TE. The clinical pregnancy and implantation rate were compared between each group. The data were analyzed by either t-test or chi-square analysis.

RESULTS

There were no statistically significant differences in average female ages, infertility factors, or the distribution of blastocyst grades A, B, and C in each group. There was no significant difference in the clinical pregnancy and implantation rate of each group according to their blastocyst grade. However, there was a significant difference in the clinical pregnancy and implantation rate between each group. In the HdB group, the clinical pregnancy and implantation rate were similar regardless of the blastocyst quality.

CONCLUSION

There was an effect on the clinical outcomes depending on whether the blastocyst hatched during single frozen-thawed blastocyst transfer. When performing single frozen-thawed blastocyst transfer, the hatching status of the frozen-thawed blastocyst may be a more important parameter for clinical outcomes than the quality of the frozen-thawed blastocyst.

Reproducibility and clinical significance of pre-ovulatory serum progesterone level and progesterone/estradiol ratio on the day of human chorionic gonadotropin administration in infertile women undergoing repeated in vitro fertilization cycles

BACKGROUND

The objective of this study was to explore the cycle-to-cycle reproducibility of serum progesterone level and progesterone/estradiol (P/E2) ratio in the final step of triggering oocyte maturation in patients undergoing repeated consecutive controlled ovarian hyperstimulation for in vitro fertilization (COH-IVF) treatment and to investigate the clinical parameters associated with serum progesterone concentration and P/E2 ratio.

METHODS

We retrospectively studied 524 cycles in 203 infertile women who underwent two or more fresh COH-IVF cycles from July 1998 to May 2012 in a university hospital IVF unit. The patients were divided into groups according to the number (2, 3 or >=4) of total successive IVF cycles with successful oocyte retrieval. The within-subject reproducibility of serum P and P/E2 was tested by calculating intra-class correlation coefficients (ICCs). Multiple linear regression analysis was used to assess the association between patient variables and pre-ovulatory serum P level and P/E2 ratio.

RESULTS

The ICCs in women who underwent 2, 3 and >=4 IVF cycles were -0.052, 0.163 and 0.212, respectively, for serum P concentration and 0.180, 0.168 and 0.148, respectively, for P/E2 ratio. All ICCs for both serum P and P/E2 ratio were indicative of poor reproducibility. The number of oocytes was significantly positively related to P concentration, and endometrial thickness was significantly negatively related to P concentration and P/E2 ratio.

CONCLUSION

The cycle-to-cycle reproducibility of pre-ovulatory serum P concentration and P/E2 ratio was poor in individual patients, and these fluctuations were more cycle- than patient-dependent. The number of oocytes was the most significant factor relating to P concentration. By using milder stimulation approach to produce fewer oocytes in the next cycle is a strategy to overcome the high serum P concentration, while clinicians should consider each patient's general condition including the age, ovarian reserve, embryo grading and the capacity of frozen-thawed embryo transfer.

Evaluation of bovine embryo biopsy techniques according to their ability to preserve embryo viability

The purpose of this research was to evaluate three embryo biopsy techniques used for preimplantation genetic diagnosis (PGD) in cattle and to recommend the least invasive one for current use, especially when PGD is followed by embryo cryopreservation. Three hundred bovine embryos were biopsied by either one of the needle, aspiration or microblade method, and then checked for viability by freezing/thawing and transplantation to recipient cows. The number of pregnancies obtained after the transfer of biopsied frozen/thawed embryos was assessed 30 days later using ultrasounds. The results were significantly different between the three biopsy methods: the pregnancy rate was of 57% in cows that received embryos biopsied by needle, 43% in cows that received embryos biopsied by aspiration, and 31% in cows that received embryos biopsied by microblade. Choosing an adequate biopsy method is therefore of great importance in embryos that will undergo subsequent cryopreservation, as it significantly influences their viability after thawing.

Current progress in oocyte and embryo cryopreservation by slow freezing and vitrification

Preservation of female genetics is currently done primarily by means of oocyte and embryo cryopreservation. The field has seen much progress during its four-decade history, progress driven predominantly by research in humans, cows, and mice. Two basic cryopreservation techniques rule the field – controlled-rate freezing, the first to be developed, and vitrification, which, in recent years, has gained a foothold. While much progress has been achieved in human medicine, the cattle industry, and in laboratory animals, this is far from being the case for most other mammals and even less so for other vertebrates. The major strides and obstacles in human and other vertebrate oocyte and embryo cryopreservation will be reviewed here.

Zona-free versus laser zona-assisted hatching blastocyst transfer: a comparison of outcomes

In unselected IVF patients, zona-free and laser zona-assisted hatching produced a comparable effect on blastocyst transfer.

The influences of weather on patients with different ovarian responses in the treatment of assisted reproductive technology

PURPOSE

The purpose of this study was to evaluate the influences of tropical weather on patients with different ovarian responses in the treatment of assisted reproductive technology.

METHODS

Six-hundred fourty-seven women underwent their first treatment cycles were retrospectively analyzed. Patients received embryo transfer either 3 days or 5 days after oocyte retrieval, depending on the number and quality of embryos on day-2.

RESULTS

Significant correlations were demonstrated in the top quality embryo rates of day-3 and day-5 embryo transfers with temperature, humidity, and atmosphere pressure. The cumulative light hours negatively correlated with the implantation and pregnancy rates of day-3 embryo transfer (-.282 and -.282, respectively), while they positively correlated with those of day-5 embryo transfer (.225 and .224, respectively).

CONCLUSIONS

These results clearly suggest that weather may exert influences on the outcome of assisted reproductive technology. Patients with different ovarian responses or blastocyst culture and transfer may modify weather influences.

Possible applications of a non-contact 1.48 μm wavelength diode laser in assisted reproduction technologies

Recently, one laser system has been introduced in IVF fulfilling all safety requirements, while achieving a high standard of reproducibility in terms of ablation diameter. This 1.48 microm wavelength indium-gallium-arsenic-phosphorus (InGaAsP) semiconductor laser offers a variety of laser applications to the embryologist. On the one hand, zona pellucida of oocytes or embryos can be manipulated in order to facilitate ICSI or biopsy and assist hatching, and on the other, spermatozoa may be paralysed or immobilized prior to usage. To conclude, the 1.48 microm diode laser provides a promising tool for the microdissection of subcellular targets. The diode laser stands out due to the rapidity, the simplicity and the safety of the procedure which is supported by healthy offspring after laser application.

Human oocyte maturity in vivo determines the outcome of blastocyst development in vitro

PURPOSE

To date, the impact of oocyte maturity at aspiration on the blastocyst formation in vitro has not been fully evaluated. This study was undertaken to assess the influence of oocyte maturity in patients undergoing in vitro fertilization and blastocyst transfer program.

METHODS

A total of 1278 oocytes derived from 147-IVF cycles were retrospectivly analyzed. Oocyte maturity was graded on a scale from 1 to 5 based on the morphology of the ooplasm, cumulus mass, corona radiata, and membrana granulosa cells.

RESULTS

Mature oocytes yielded the highest fertilization rates. Although the cleavage rates were similar in both groups, the percentage of poor morphology, day-3 embryos from the nonmature-oocyte group was significantly higher than from the mature-oocyte group (54.7% vs. 15.5%, P < 0.001). Although good morphology, day-3 embryos were collected from nonmature oocytes, the incidence of these embryos developing to the blastocyst stage was significantly less than from mature oocytes (33.3% vs. 71.2%, P < 0.001). Although blastocyst stage embryos were collected from nonmature oocytes, the incidence of these embryos developing to the top-scoring blastocysts was significantly less than from mature oocytes (58.3% vs. 89.5%, P < 0.001).

CONCLUSIONS

These phenomena suggest that oocyte maturity produced in vivo determine the fertilization potential and subsequent blastocyst quality in vitro.

Assisted hatching improves implantation rates on cryopreserved-thawed embryos. A randomized prospective study

BACKGROUND

Focus on the hatching process has so far been in the field of fresh embryos. Cryopreserved-thawed embryos have a lower rate of pregnancy than fresh embryos, which might be due to hardening of the zona pellucida.

METHODS

During a 2 year period, a prospective randomized study enrolling 253 cryopreserved-thawed cycles was performed on day 2 embryos. Pseudorandomization to assisted hatching or a control group was done on the basis of even and odd dates for thawing. One hour before embryo transfer, hatching was carried out using acidic Tyrode's solution.

RESULTS

Among 136 embryos exposed to assisted hatching, 11.4% (30) were implanted compared with only 5.8% (13) of 117 embryos not exposed to assisted hatching (P<0.05, chi(2) test). No difference in the rate of clinical pregnancy and positive serum HCG was observed between the two groups. Very few women >38 years old were included in the study, and no significant difference according to age could be found between the groups.

CONCLUSIONS

These results show that assisted hatching using acidic Tyrode's solution increases the implantation rate of cryopreserved-thawed embryos (P<0.05).

Transfer of nonselected transferable day 3 embryos in low embryo producers

OBJECTIVE

To examine the implantation potential of embryos from assisted reproductive technology cycles with low embryo production and to assess the effects of clinical variables and embryo scores (ES) on pregnancy outcome.

DESIGN

Prospective clinical study.

SETTING

Assisted reproductive technology unit in a tertiary medical center.

PATIENT(S)

From July 1998 to December 2001, 280 cycles in 229 infertile couples produced a limited number of one, two, or three embryos 3 days after oocyte retrieval and underwent fresh embryo transfer (ET).

INTERVENTION(S)

Embryos with two or more blastomeres were scored and transferred.

MAIN OUTCOME MEASURE(S)

ES and implantation rate per ET.

RESULT(S)

Of 863 fresh ET cycles during the study period, 32.4% (280) were low embryo producers. Among them, there were no significant differences in average ES of individual embryos in single, dual, or triple ET or in embryos obtained from patients with low or high E2 responses, or young or old age. Embryos derived from conventional IVF had a better ES than those derived from intracytoplasmic sperm injection. The clinical pregnancy rate was strongly correlated with the cumulative ES. Implantation rates were similar among and between groups, with an average rate of 15.9%.

CONCLUSION(S)

Embryos of low embryo producers had an inherently low implantation potential that appeared to be unrelated to the number of embryos transferred, female age, ovarian E2 genesis, or fertilization method. The cumulative ES can serve as a predictor of pregnancy.