Morphology of vitrified/warmed day-5 embryos predicts rates of implantation, pregnancy and live birth

Single day 14 serum hCG values allow prediction of viable pregnancy and are significantly higher in frozen as compared to fresh single blastocyst transfer

PURPOSE

To evaluate if single serum human chorionic gonadotropin (hCG) level measurements are sufficient for pregnancy monitoring after single embryo transfer (sET) and to compare the hCG levels between fresh (FRET) and frozen embryo transfers (FET) in medically assisted reproduction.

METHODS

This was a retrospective exploratory cohort study including all patients who met the inclusion criteria, who received a single FRET (n = 249) or FET (n = 410) of a day five blastocyst at the IVF clinic at the Johannes Kepler University Linz between 2011 and 2020. hCG levels were measured on day 14 after embryo transfer. Threshold values for the viability of pregnancies were determined using receiver operating characteristic (ROC) curves.

RESULTS

Significantly higher hCG levels were found in those who received FET than in those who received FRET (1222.8 ± 946.7 mU/ml vs. 862.7 ± 572.9 mU/ml; p < 0.001). Optimal threshold values predicting a viable pregnancy were 368.5 mU/ml and 523 mU/ml in the FRET and FET groups, respectively.

CONCLUSIONS

After FET, higher hCG values after 14 days of embryo transfer must be considered in pregnancy monitoring. Additionally, a single threshold hCG value seems to be sufficient for determining pregnancy viability. To exclude ectopic pregnancies, subsequent ultrasound examination is a mandatory requirement.

Pre-Vitrification and Post-Warming Variables of Vitrified-Warmed Blastocysts That Are Predictable for Implantation

Human IVF embryos that are not used for fresh transfer are cryopreserved by vitrification for later embryo transfers. This study evaluates pre-vitrification and post-warming embryo characteristics that are suitable to predict the chance of clinical pregnancy in single vitrified blastocyst transfer (SVBT) cycles. In a multicenter observational trial (IMBOS trial), embryos were cultured in a time-lapse system before and after vitrification. Associations between clinical pregnancy, morphokinetic parameters, blastocyst collapse, KIDScore D5, pre-vitrification and post-warming Gardner scores, post-warming blastocyst size and re-expansion rates before SVBT were analyzed in 182 SVBTs which resulted in 89 clinical pregnancies. No association was found between clinical pregnancy after SVBT and the number of collapses or the maximal collapse size before vitrification. The multifactorial analysis of pre-vitrification Gardner scores showed a significant association with clinical pregnancy for trophectoderm grading but not for expansion/hatching status and inner cell mass grading. A significant association with clinical pregnancy was found for the time to reach a blastocyst after pronuclear fading (tB-tPNf), KIDScore D5 and post-warming size but not the rate of expansion or maximal expansion size. The selection of blastocysts for SVBT could benefit from using pre-vitrification parameters like tB-tPNf, trophectoderm grading and post-warming blastocyst size.

Freeze all-first versus biopsy-first: A retrospective analysis of frozen blastocyst transfer cycles with preimplantation genetic testing for aneuploidy

Potential use of preimplantation genetic testing for aneuploidy (PGT-A) is increasing. Patients who have excess embryos cryopreserved at the blastocyst stage may desire PGT-A but there is little data available on options for these patients. We compared the efficacy and safety of the timing on the cryopreservation and trophectoderm(TE) biopsy for preimplantation genetic testing for aneuploidy (PGT-A) program associated with the better outcomes after frozen blastocyst transfer. Retrospective analysis of patients who underwent PGT-A cycles from January 2016 to December 2019 was carried out. 2684 blastocysts from cycles were subjected to TE biopsy for performing array comparative genomic hybridization test and Next-generation sequencing. All cycles were divided into two according to the timing of biopsy: biopsy-first (n = 211 cases/ 232 transfers) versus freeze all-first (n = 327 cases/ 415 transfers). In the biopsy-first group, embryos were cultured to expanded blastocyst and proceed to TE biopsy on day 5 or day 6 followed by cryopreservation. In the freeze all-first, blastocysts were vitrified and warmed before biopsy. Rates of clinical pregnancy (52.3% vs. 38.7%, P = 0.09) and ongoing pregnancy (44.3% vs. 34.5%, P = 0.07) in biopsy-first were significantly higher than those in freeze all-first. Biopsy-first showed comparable miscarriage rate with freeze all-first (15.2% (33/217) vs.11.1% (10/90), respectively). Rate ratio (RR) for clinical pregnancy was lower in freeze all-first group (adjusted RR = 0.78, 95% confidence interval: 0.65, 0.93). The RRs for miscarriage and live birth was also lower but it did not reach statistical significance. Our result supported performing TE biopsy of blastocyst for PGT-A before vitrification and warming. This finding would contribute to more evidence-based decision in PGT-A cycles.

What to advise to patients with only one good quality blastocyst, PGT-A or not? Outcomes of 2064 cycles

PURPOSE

To evaluate whether preimplantation genetic testing for aneuploidy (PGT-A) is beneficial for patients who have only one blastocyst available for biopsy or transfer.

METHODS

This retrospective study was based on 1126 single blastocyst PGT-A and 938 non-PGT-A cycles, a total of 2064 ART cycles which resulted in a single good quality blastocyst in women between 20 and 45 years old. The PGT-A group had 225 single euploid embryo transfer cycles and the non-PGT-A group had 938 single blastocyst embryo transfer cycles.

RESULTS

In the generalized linear mixed model (GLMM), female age and PGT-A variables were found to be significant variables on pregnancy outcomes. In the PGT-A cases, regardless of the effect of other variables, the probabilities of clinical pregnancy and live birth were found to be 3.907 and 3.448 fold higher respectively than in the non-PGT-A cases (p < 0.001). In non PGT-A cases, the probability of a total pregnancy loss was found to be 1.943 fold higher (p = 0.013).

CONCLUSION

PGT-A in the presence of a single blastocyst significantly increases clinical pregnancy and live birth rates and decreases total pregnancy losses regardless of age. In addition, aneuploid embryo transfer cancelations prevent ineffective and potentially risky transfers.

Standardization of Post-Vitrification Human Blastocyst Expansion as a Tool for Implantation Prediction

The increased use of vitrified blastocysts has encouraged the development of various criteria for selecting the embryo most likely to implant. Post-thaw assessment methods and timetables vary among investigators. We investigated the predictive value of well-defined measurements of human blastocyst re-expansion, following a fixed incubation period. Post-thaw measurements were taken exactly at 0 and 120 ± 15 min. Minimum and maximum cross-sectional axes were measured. Three groups were defined: Group 1: embryos that continued to shrink by 10 µm or more; group 2: embryos that ranged from −9 to +9 µm; and group 3: re-expansion of 10 µm or more. Patient and morphokinetic data were collected and integrated into the analysis. A total of 115 cases were included. The clinical pregnancy rate for group 1 was 18.9%; group 2, 27%; and group 3, 51.2% (p = 0.007). Pre-thaw morphologic grading and morphokinetic scores of the study groups did not reveal differences. p-values were 0.17 for the pre-thaw morphologic score, 0.54 for KID3, and 0.37 for KID5. The patients’ demographic and clinical data were similar. The clinical pregnancy rate correlated with the degree of thawed blastocyst re-expansion measured 2 h after incubation. This standardized measure is suggested as a tool to predict the potential of treatment success before embryo transfer.

Post-warming embryo morphology is associated with live birth: a cohort study of single vitrified-warmed blastocyst transfer cycles

Purpose

This study aims to examine whether blastocyst morphology post-warming correlates with live birth.

Methods

In this cohort study, morphological characteristics post-warming were reviewed in all single vitrified-warmed blastocyst transfer cycles performed between November 2016 and May 2017. Immediately before transfer, the degree of blastocoel re-expansion was graded as A, fully expanded; B, partially expanded ≥ 50%; C, partially expanded < 50%; and D, collapsed. The degree of post-warming cell survival was graded on a scale of 50 to 100% and was then classified into 4 groups: very low 50–70%, low 71–80%, moderate 81–90%, and high 91–100%.

Results

Overall, 612 cycles were reviewed, of which 196 included PGT-A tested embryos. The live birth rate (LBR) increased from 11.4% in the collapsed blastocysts group to 38.9% in the post-warming full re-expansion group (p < 0.001) and from 6.5% for blastocysts with a very low cell survival rate to 34.7% for blastocysts with high cell survival rate (p = 0.001). LBR was 6.7% for blastocysts with the worst post-warming morphological characteristics, namely, collapsed with very low cell survival rate. On multivariate analyses, partial blastocyst re-expansion ≥ 50%, full re-expansion, and high cell survival rate remained significantly associated with live birth, after controlling for female age, pre-vitrification morphological grading, and PGT-A. A sub-analysis of cycles using PGT-A tested embryos showed similar results.

Conclusion

Post-warming re-expansion and high cell survival rate are associated with higher LBR in euploid and untested blastocysts. However, embryos with poor post-warming morphology still demonstrate a considerable probability of live birth, and they should not be discarded.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10815-021-02390-z.

Use of a new set of key performance indicators for evaluating the performance of an in vitro fertilization laboratory in which blastocyst culture and the freeze-all strategy are the primary treatment in patients with in vitro fertilization

Objective

To evaluate the performance of an in vitro fertilization (IVF) laboratory using a new set of key performance indicators (KPIs) when the main treatment of IVF patients had been changed.

Methods

Patients who underwent fresh embryo transfer and the freeze-all strategy in August, September, and October 2017 were retrospectively studied to evaluate the performance of an IVF laboratory in September when implantation rate of fresh embryo transfer decreased. KPIs associated with blastocyst culture and the first frozen embryo transfer (FET) cycle in patients with the freeze-all strategy were compared over 3 months.

Results

Day 5 usable blastocyst and good quality blastocyst rates, and day 3 usable/good quality embryo rates were not different among the three periods. The implantation rate and KPIs associated with morphological changes in warmed blastocysts in the first FET cycle in patients with the freeze-all strategy were also not different among the periods.

Conclusions

KPIs associated with embryo quality, blastocyst culture, and the pregnancy outcome of the first FET cycle in patients with the freeze-all strategy suggested that performance was unaffected in our IVF laboratory in September. These KPIs might be useful for internal quality control analysis of IVF laboratories.

Embryo re-expansion does not affect clinical pregnancy rates in frozen embryo transfer cycles: a retrospective study

PURPOSE

A retrospective study examining the effects of embryo re-expansion before transfer on pregnancy outcomes for frozen embryo transfers (FET).

METHODS

A total of 486 FET cycles from November 2017 through December 2019 were studied. These cycles included patients using autologous, donor oocytes, and donor embryo with patients ranging from ages 23 to 48 years with infertility diagnoses. Programmed FET priming was performed with exogenous estrogen and progesterone. All blastocysts were cultured in trigas incubators for 20 min to 4 h and 42 min. Pictures of each blastocyst after thaw and before transfer were taken utilizing the Hamilton Thorne Zilos laser software (Beverly, MA). The longest portion of the embryo was measured in µm. Pregnancy was defined by a positive hCG, and ongoing clinical pregnancy was defined by the presence of fetal cardiac activity. Wilcoxon rank sum tests were used to access differences in change parameters.

RESULTS

There is no significant difference in the amount of embryo expansion or contraction to achieve an ongoing pregnancy. The difference remained non-significant when stratified by embryo expansion or contraction. The amount of change over time and percent change from the first measurement were also not associated with achieving an ongoing pregnancy. This remained true after adjustment for patient age and whether or not a biopsy was performed.

CONCLUSIONS

Embryos that do not re-expand after warming appear to have a similar chance of achieving a successful pregnancy as those that do re-expand.

Prediction of embryo survival and live birth rates after cryotransfers of vitrified blastocysts

RESEARCH QUESTION

Which pre-vitrification parameters are the most predictive of survival and live birth in vitrified-warmed blastocyst transfer cycles?

DESIGN

A retrospective study including 11,936 warmed blastocysts. Pre-vitrification morphological parameters analysed for blastocysts included day of vitrification; blastocyst expansion degree; trophoectoderm grade (A, B and C); and inner cell mass grade (A, B and C). Univariate and multivariate generalized estimating equations models were used to analyse survival, clinical pregnancy and live birth rate. A stepwise regression analysis was conducted to select and classify by order which outcomes were the most predictive.

RESULTS

The odds of survival increased almost twice for blastocysts with lower expansion degree (OR 1.92; 95% CI 1.37 to 2.69; P < 0.001) and by about 50% for blastocysts vitrified on day 5 (OR 1.56; 95% CI 1.27 to 1.89; P < 0.001). Multivariate generalized estimating equations model showed that trophectoderm grade followed by the day of vitrification were the most significant predictors of live birth. The odds of live birth increased nearly three times for blastocysts with trophectoderm graded as A compared with those with trophectoderm graded as C (OR 2.85; 95% CI 2.48 to 3.27; P < 0.001), and double for blastocysts vitrified on day 5 compared with those vitrified on day 6 (OR 2.22; 95% CI 1.97 to 2.49; P < 0.001). The odds of live birth also increased in higher expansion degree blastocysts.

CONCLUSIONS

Blastocysts vitrified on day 5 and those with higher trophoectoderm grade should be given priority when warming.

Blastocyst age, expansion, trophectoderm morphology, and number cryopreserved are variables predicting clinical implantation in single blastocyst frozen embryo transfers in freeze-only-IVF

PURPOSE

To determine which blastocyst assessment variables predict clinical implantations in single blastocyst frozen embryo transfers (FET) of freeze-only-IVF cycles, following improved vitrified-warmed blastocyst survival and developmental competence preservation.

METHOD

In this retrospective cohort study performed at a single private IVF center, the pregnancy outcomes of 1795 single blastocyst FET cycles were analyzed, from freeze-only-IVF retrievals performed between January 2017 and January 2020. Stepwise forward logistic regressions with clinical implantation (i.e., normal gestational sac and cardiac activity) as dependent variable were performed to identify the significant predictors. All blastocysts were vitrified using Cryotop technology, with before transfer (post-warming) blastocyst morphology scores used in all analyses.

RESULT(S)

The 1795 blastocysts transferred were vitrifıed on embryo days 4 (1057), 5 (716), and 6 (22). The overall clinical implantation rate was 50.9%; however, using blastocyst age and blastocyst morphological score the clinical implantation rates increased from 49.0% (day-4 1 and 2) and 25.2% (day-5 1 and 2) to 71.2% (day-4 4AA) and 64.3% (day-5 4AA), respectively. Whereas full (≥3) blastocysts with scores of AA and BA had similar clinical implantation rates (66.2 vs. 66.7%), the rate of full blastocysts with scores of AB was lower (58.9%). In stepwise forward logistic regressions, female age, blastocyst age, blastocyst expansion score, blastocyst trophectoderm score, and number of blastocysts vitrified were significant predictors of clinical implantation.

CONCLUSION(S)

Using blastocyst age and before transfer blastocyst expansion and trophectoderm morphology scores to select blastocysts, clinical implantation rates greater than 70% could be achieved for top-scoring blastocysts.

Incidence of multiple births in relation to current regulations in Turkey regarding embryo transfer

Background

Before 2010, there were no regulations in Turkey regarding the number of embryos to be transferred in one cycle. In March 2010, regulations restricting this number were implemented by the Turkish Ministry of Health. These specify the transfer of a maximum of one embryo in the first and second cycles and a maximum of two embryos in subsequent cycles in women aged < 35, and a maximum of two embryos in women aged ≥35 in any one cycle. Our study evaluates the effect of these regulations.

Methods

This large retrospective single center study first evaluates the incidence of multiple pregnancies before and after the implementation of the 2010 regulations. Secondly, it compares the clinical outcomes of double blastocyst transfer (DBT) and single blastocyst transfer (SBT) performed in compliance with these regulations from 2014 onwards.

Results

After the introduction of the 2010 regulations, the multiple pregnancy rate decreased significantly from 37.9 to 15.7%. The singleton live birth rate increased significantly, whereas multıiple live birth rates significantly decreased (p = < 0.001).

When the clinical outcomes of SBT and DBT performed in compliance with regulations from 2014 onwards were evaluated, in patients < 35 years, the multiple pregnancy rate decreased from 47.2% in the DBT group to 1.7% in the SBT group (p = < 0.001). In patients ≥35 years, in the DBT group, the twin birth rate was again high at 28.4%, whereas in the SBT group, it was only 1.8% (p = < 0.001). Importantly, there was no statistically significant difference in clinical pregnancy rates between these two groups.

Conclusion

Turkish regulations have led to an encouragement of double embryo transfer (DET) as a routine practice, with many patients understanding it as an absolute right to have two embryos transferred. The results of our study suggest that, especially in the light of the success of blastocyst transfer, the Turkish regulations should be amended to limit the use of DET and encourage the use of single embryo transfer except in exceptional cases and particularly in women under 35 years old.

Does fresh single embryo transfer outcome predict the result of a subsequent vitrified-warmed blastocyst of the same cohort?

Reflecting the current trends, the utilization of frozen-thawed transfer cycles has been steadily increasing worldwide; outcome predictors of these cycles are therefore a major research goal. Our aim was to investigate whether the outcome of a fresh single blastocyst transfer (SBT) can serve as a prognostic factor for the subsequent vitrified-warmed SBT originating from the same cohort. A retrospective cohort study was performed at a single unit. Non-donor fresh cycles were analyzed as predictors of the following vitrified-warmed cycle. Only SBTs were included. Cycles designated to a freeze-all policy and cycles involving pre-implantation genetic analysis were excluded. A total of 1127 vitrified-warmed single blastocyst cycles were included. The indications for artificial reproductive technologies were comparable across the study groups. Vitrified-warmed cycles following a live birth outcome in the fresh cycle were more likely to result in a clinical pregnancy than those following a fresh cycle, which failed to reach a live birth. The same trend was observed for live birth rate following vitrified-warmed transfer in the fresh cycle. After correcting for possible confounders, age and embryo quality were significantly correlated with the chance for a live birth, but the previous fresh cycle did not affect the results. We therefore conclude that after adjustment for age, embryo quality and number of previous oocyte retrieval cycles, the fresh cycle outcome was not a significant influential factor for the following vitrified-warmed cycle.

High rates of aneuploidy, mosaicism and abnormal morphokinetic development in cases with low sperm concentration

Purpose

The aim of our study was to evaluate the impact of severe male infertility (SMF) on the chromosomal status of embryos and any possible correlation between chromosomal status and embryo morphokinetics in younger women using data obtained from comprehensive preimplantation genetic tests.

Methods

The trial was conducted in an ART and Reproductive Genetics Centre between 2011 and 2018. A total of 326 cycles in cases with SMF where the female partner’s age was ≤ 35 years were evaluated. SMF is defined as sperm concentration below 5 mil/ml (million per milliliter) and divided into three subgroups according to sperm concentrations: 1–5 mil/ml, < 1mil/ml and testicular sperm. The control group of 190 cycles had normal sperm parameters.

Results

Significantly lower chromosomal euploidy rates were found in the testicular sperm group compared with the normal sperm controls when the female age was ≤ 35 years. In SMF, statistically significantly affected chromosomes were 2, 10, 11, 17, 21 and sex chromosomes. The mosaicism and abnormal morphokinetic development rates were higher in the SMF group than in control group, and this difference was significant when testicular sperm was used.

Conclusion

Lower euploidy rates, higher mosaicism rates and a higher incidence of abnormal morphokinetic development were observed in cases with testicular sperm with female partners ≤ 35 years compared with normal sperm controls. These findings suggest that PGT-A may be advisable in severe male infertility cases. Furthermore, the correlation between morphokinetics and chromosomal status was greatly reduced or absent in these most severe forms of male infertility, thus the need for new morphokinetic models.

Electronic supplementary material

The online version of this article (10.1007/s10815-019-01673-w) contains supplementary material, which is available to authorized users.

Time-lapse imaging of cytoplasmic strings at the blastocyst stage suggests their association with spontaneous blastocoel collapse

RESEARCH QUESTION

To study the origin and temporal behaviour of cytoplasmic strings spanning the blastocoel (main objective) and their influence on treatment outcome (secondary objective).

DESIGN

This retrospective analysis of prospectively collected data was set up in a university medical centre. Patients who either underwent fresh (n = 95) or vitrified-warmed (n = 55) single blastocyst transfer were included. Time-lapse sequences of in-vitro developed blastocysts were screened for the presence of cytoplasmic strings. Pregnancies in string-positive and string-negative transfers were followed up to live birth.

RESULTS

A total of 387 blastocysts were obtained in the fresh cycles of 100 patients, corresponding to a blastocyst formation rate of 62.4%. Cytoplasmic strings were first detected around full stage (108.5 ± 6.4 h) in 170 blastocysts (43.9%). The number of strings varied (range: 1-7) and the duration of visibility was 5.2 ± 3.5 h. The occurrence of cytoplasmic strings was significantly associated with the presence of blastocoelic collapses (P < 0.001) but not with any of the annotated morphokinetic parameters. Live birth and neonatal outcome were the same for both string-positive and string-negative pregnancies. Moreover, collapses did not affect treatment outcome.

CONCLUSION

Time-lapse analysis of cytoplasmic strings at the blastocyst stage revealed that this morphological feature was not a negative predictor as previously reported. Although physiologically normal, at least some of the cytoplasmic strings are an artefact, possibly associated with blastocoelic collapses.

Blastocoele expansion: an important parameter for predicting clinical success pregnancy after frozen-warmed blastocysts transfer

OBJECTIVE

To assess the predictive value of each individual morphological parameter: blastocoele expansion degree, inner cell mass (ICM), and trophectoderm (TE) grades on the clinical pregnancy outcome in frozen-warmed embryo transfer (FET) cycles.

METHODS

This is a retrospective cohort study, including 1154 FET cycles receiving vitrified-warmed one or two blastocysts transfer from August 2011 through to May 2018. The correlation between blastocyst morphology parameters and clinical outcome after FET was assessed.

RESULTS

In the subgroup analysis based on clinical pregnancy, the patients who achieved clinical pregnancy had a significantly higher degree of blastocyst expansion (3.69 ± 0.68 vs. 3.53 ± 0.78, P = 0.000) and had a thicker endometrium (9.65 ± 1.63 vs. 9.28 ± 1.64) compared with those with non-clinical pregnancy. The logistic regression analysis showed that among the three blastocyst morphology parameters, only the blastocoele expansion degree was significantly correlated with the clinical pregnancy outcome and had ability to predict the outcome after FET cycles with one or two vitrified-warmed blastocysts transferred. Both ICM and TE stages were not associated with pregnancy outcomes.

CONCLUSIONS

The blastocoele expansion degree may be essential for successful pregnancy and should be given priority when selecting frozen blastocyst for transfer.

Transdermal versus oral estrogen: clinical outcomes in patients undergoing frozen-thawed single blastocyst transfer cycles without GnRHa suppression, a prospective randomized clinical trial

Purpose

To conduct a non-inferiority study to compare the clinical outcomes of transdermal estrogen patch and oral estrogen in patients undergoing frozen-thawed single blastocyst transfer non-donor cycles without GnRHagonist (GnRHa) suppression.

Methods

A total of 317 women with irregular menses or anovulatory cycle undergoing frozen-thawed embryo transfer (FET) non-donor cycles without GnRHa suppression were involved in a prospective randomized clinical trial between May 2017 and October 2017. The trial was conducted in an ART and Reproductive Genetics Centre within a private hospital. The unit is designated as a teaching center by the Turkish Ministry of Health. Oral or transdermal estrogen was administered in patients undergoing frozen-thawed single blastocyst transfer. The outcomes of the study were the following: endometrial thickness on the day of progesterone administration, implantation rate, and clinical and viable ongoing pregnancy rates.

Results

Endometrial thickness and clinical outcomes of oral and transdermal estrogen administration were equally successful (p > 0.05).

Conclusion

No significant difference was found in endometrial thickness on the day of progesterone administration nor in clinical outcomes between transdermal estrogen and oral estrogen in patients undergoing frozen-thawed single blastocyst stage transfer cycles without GnRHa suppression.

A comparison of the survival and implantation rates of blastocysts that were vitrified on post-fertilization day five, six and seven

The goal of this retrospective cohort study was to compare survival, implantation, clinical and ongoing pregnancy rates between blastocysts that were vitrified on post-fertilization days 5, 6 and 7. Before vitrification, blastocysts were evaluated in terms of morphology and blastocyst expansion, inner cell mass and trophectoderm quality. They were thawed and transfered in a subsequent artificial cycle. Embryo implantation rates were 39%, 25% and 25% for blastocysts that were vitrified on days 5, 6, and 7, respectively (p = 0.006). Clinical and ongoing pregnancy rates were 19%, 12%, 13% (p = 0.100) and 9%, 7%, 12% (p = 0.99) for days 5, 6 and 7 blastocysts, respectively. Day 5 blastocysts had significantly higher full-collapsing score after assisted-hatching compared to days 6 and 7 blastocysts (p = 0.014). As blastocyst quality increased, implantation and clinical pregnancy rates increased in all groups and both parameters were statistically significantly higher on day 5 blastocysts than on days 6 or 7 (p = 0.001). It was clearly found that good quality blastocysts obtained on day 5 have higher implantation and clinical pregnancy rates than 6th and 7th day cryopreserved embryos. There were no statistically significant differences between the cryopreserved embryos on days 6 and 7 regarding the implantation, clinic and ongoing pregnancy rates.

Morphokinetics of vitrified and warmed blastocysts predicts implantation potential

PURPOSE

It was studied whether morphokinetics of blastocoele re-expansion and hatching in vitrified-warmed blastocysts is predictive of implantation, clinical pregnancy, and live birth.

METHODS

In 144 patients aiming for single warmed blastocyst transfer, blastocysts were cultured in a new time-lapse system (Miri® TL) immediately after warming. Video sequences with an image interval of 5 min were annotated and the corresponding morphokinetic variables were correlated with pregnancy outcome. In detail, tRE (start of re-expansion), tCRE (completion of re-expansion), tAH (hatching from the manipulated zona pellucida), and presence of collapses were recorded.

RESULTS

In the pregnant group, tRE and tCRE were significantly lower (0.69 ± 0.45 h and 2.16 ± 0.94 h) as compared to the non-pregnant group (1.23 ± 1.08 h and 2.70 ± 1.20 h). Both variables and the duration of re-expansion (tCRE-tRE) allowed for distinction between "non-pregnant," "loss of pregnancy," and live birth/ongoing pregnancy. Presence and number of collapses showed no correlation with outcome.

CONCLUSIONS

Time-lapse imaging of vitrified-warmed blastocysts offers additional selection criteria allowing for prediction of implantation potential. As a consequence, cumulative pregnancy rate could be increased and time-to-pregnancy reduced.

Factors associated with birth outcomes from cryopreserved blastocysts: experience from 4,597 autologous transfers of 7,597 cryopreserved blastocysts

OBJECTIVE

To evaluate factors associated with cryopreserved blastocyst transfer birth outcomes, including age, expansion time, cryopreservation protocol, cryodamage, and number of embryos transferred.

DESIGN

Retrospective cohort study.

SETTING

Private infertility practice.

PATIENT(S)

Cryopreserved blastocyst transfer patients from January 2003 to April 2012.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Birth per transfer and children per embryo.

RESULT(S)

Overall live birth per transfer was 32%, with 17% twin births and 0.3% triplets. Live birth per transfer was significantly higher for vitrification compared with slow-freeze (day 5 cryopreservation: 47% vs. 35%; day 6 cryopreservation: 46% vs. 24%), as was live born children per transferred embryo (39% vs. 29% for day 5; 36% vs. 18% for day 6). Birth rates declined only slightly with increasing age at cryopreservation through 37 years, followed by an increasingly rapid decline in success with increasing age thereafter. Live birth rates declined rapidly (49%-18% for vitrification and 37%-10% for slow-freeze) as the percentage of intact cells after cryopreservation decreased from 95%-100% to 70%-79%, with almost no births when the percentage of intact cells was <70%. Increasing numbers of embryos per transfer were associated with significant increase in live birth per transfer but significant decrease in children per transferred embryo. Birth rates were much lower for blastocysts with delayed expansion on day 7 (10% per transfer).

CONCLUSION(S)

Birth outcomes from cryopreserved blastocyst transfer are influenced by age, timing of expansion, cryopreservation protocol, visible cryodamage, and the number of embryos transferred. Vitrification substantially improves outcomes versus slow freezing.

Use of the CryoPredict algorithm to predict live birth from cryopreserved embryos

BACKGROUND

Currently, the viability of cryostored blastocysts that are subsequently re-warmed is determined via the percentage of cell survival. However, the large number of cells that forms the blastocyst can make this estimate difficult and unreliable. Studies have shown that fast re-expanding blastocysts have superior pregnancy rates.

AIM

To determine whether the degree and speed of blastocoele re-expansion following cryopreservation and warming correlate with rates of live birth.

MATERIALS AND METHODS

A retrospective cohort study of 757 frozen embryo transfer cycles over a 4-year period at Royal Prince Alfred Hospital, Sydney. Clinical and embryology notes were retrieved. Details regarding patient demographics, stimulation cycle from which embryos were derived, frozen embryo transfer cycles, embryology and pregnancy outcomes were recorded.

RESULTS

Female (P = 0.01) and male age (P = 0.02) at the time of embryo creation were inversely associated with live birth. Fertilisation method (P = 0.03), embryo type at cryopreservation (P = 0.009), embryo grade at cryopreservation (P < 0.0001), percentage of cell survival post-thaw (P < 0.0001) and the degree of re-expansion (P = 0.003) were the IVF and embryology factors significantly associated with live birth. A predictive model (CryoPredict) was created in order to individualise the probability that the transfer of a given embryo would result in live birth.

CONCLUSIONS

The degree and speed of blastocoele re-expansion postcryopreservation and subsequent warming can be used in conjunction with other parameters to predict live birth.

Quantitative and qualitative trophectoderm grading allows for prediction of live birth and gender

PURPOSE

Prolonged in vitro culture is thought to affect pre- and postnatal development of the embryo. This prospective study was set up to determine whether quality/size of inner cell mass (ICM) (from which the fetus ultimately develops) and trophectoderm (TE) (from which the placenta ultimately develops) is reflected in birth and placental weight, healthy live-birth rate, and gender after fresh and frozen single blastocyst transfer.

METHODS

In 225 patients, qualitative scoring of blastocysts was done according to the criteria expansion, ICM, and TE appearance. In parallel, all three parameters were quantified semi-automatically.

RESULTS

TE quality and cell number were the only parameters that predicted treatment outcome. In detail, pregnancies that continued on to a live birth could be distinguished from those pregnancies that aborted on the basis of TE grade and cell number. Male blastocysts had a 2.53 higher chance of showing TE of quality A compared to female ones. There was no correlation between the appearance of both cell lineages and birth or placental weight, respectively.

CONCLUSIONS

The presented correlation of TE with outcome indicates that TE scoring could replace ICM scoring in terms of priority. This would automatically require a rethinking process in terms of blastocyst selection and cryopreservation strategy.

Validation of microSecure vitrification (μS-VTF) for the effective cryopreservation of human embryos and oocytes

A novel, aseptic closed system vitrification (VTF) technique for the cryopreservation of embryos and oocytes has been developed and clinically validated in this study. It combines the practicality of embryo-containing sterile flexipettes stored safely and securely with 0.3 ml CBS™ embryo straws possessing weld seals. The cooling and warming rates of this double container system were determined using a data logger. Upon direct plunging into LN(2), the flexipettes cool at an average rate of 1391°C/min, while warming occurs at an average rate of 6233°C/min in a 37°C 0.5 M sucrose bath. Direct deposition of the flexipette into a warming bath insured a rapid transition between -100 and -60°C to minimize potentially harmful recrystalization associated with devitrification. In conclusion, the μS-VTF system has exhibited higher (p<0.05) intact survival, implantation and live birth rates than conventional slow freezing methods. The effective embryo transfer of vitrified blastocysts proved similar to or better than fresh embryo transfer outcomes. The sustained clinical use of μS-VTF has justified a change in our infertility practice. Capsule: The microSecure vitrification (μS-VTF) procedure is a low-cost, non-commercial, aseptic, closed system that offers technical simplicity and repeatability, while effectively attaining an estimated 4:1 warming-to-cooling rate ratio, which supports excellent embryo survival and sustained viability.

[Vitrification: Principles and results]

Sperm and embryos cryopreservation is a commonly applied technique for several years. Recently authorized in France, vitrification tends to replace gradually the conventional technique of slow freezing, so upsetting the practices in the management of patients. It allows from now on the cryopreservation of oocytes and opens new perspectives in egg donation either still in fertility preservation. This review thus attempted to examine the contribution of vitrification in the freezing of oocytes and human embryos at various stages of development. If obviously vitrification appears as the current method of choice for the cryopreservation of oocytes as well as blastocysts, the results are less cut as regards embryos to early stages. No increase in adverse obstetric and perinatal outcomes in children conceived from vitrified oocytes or embryos is noted in the literature.

Survival, re-expansion and cell survival of human blastocysts following vitrification and warming using two vitrification systems

PURPOSE

This study evaluated and compared survival, re-expansion, and percentage of live cells of individual Days 5 and 6 human blastocysts that were vitrified and warmed with the Vit Kit Freeze/Thaw (Irvine Scientific, CA), or with two protocols using the Global Fast Freeze/Thaw Kits (LifeGlobal, Canada).

METHODS

Frozen/thawed Day 2-3 or discarded embryos were cultured to blastocyst (culture day 5-6). Group 1 blastocysts were vitrified with the Vit Kit (n = 29) and High Security Vitrification (HSV) devices. Group 2 (n = 47) and Group 3 (n = 48) blastocysts were cryopreserved with the Global Fast Freeze Kit and 0.25 ml straws, using a direct plunge or a -100 °C holding step, respectively. Group 4 (Controls, n = 30) were not vitrified. Blastocysts were subsequently cultured for 24 h, assessed for survival and expansion, and then stained individually with propidium iodide and Hoechst. Live and total cell number was assessed with ImageJ (NIH), and the percentage of live cells calculated for each blastocyst.

RESULTS

The percentage of live cells was not different between vitrified and control (non-vitrified) blastocysts, thus vitrification did not affect cell survival. Survival (following thawing and after 24 h culture), re-expansion, and percentage of live cells were not different for blastocysts vitrified and warmed between the two vitrification/warming kits, or between the two protocols for the Global Fast Freeze/Thaw Kits.

CONCLUSIONS

Blastocyst vitrification can be achieved with equal success using simplified protocols and cheaper and easy to load freezing straws, providing simultaneously increased safety, and efficiency with lower cost, when compared with vitrification using specialized embryo vitrification devices.

Cryopreservation of embryos and oocytes in human assisted reproduction

Both sperm and embryo cryopreservation have become routine procedures in human assisted reproduction and oocyte cryopreservation is being introduced into clinical practice and is getting more and more widely used. Embryo cryopreservation has decreased the number of fresh embryo transfers and maximized the effectiveness of the IVF cycle. The data shows that women who had transfers of fresh and frozen embryos obtained 8% additional births by using their cryopreserved embryos. Oocyte cryopreservation offers more advantages compared to embryo freezing, such as fertility preservation in women at risk of losing fertility due to oncological treatment or chronic disease, egg donation, and postponing childbirth, and eliminates religious and/or other ethical, legal, and moral concerns of embryo freezing. In this review, the basic principles, methodology, and practical experiences as well as safety and other aspects concerning slow cooling and ultrarapid cooling (vitrification) of human embryos and oocytes are summarized.

Vitrified blastocysts from Preimplantation Genetic Diagnosis (PGD) as a source for human Embryonic Stem Cell (hESC) derivation

Embryos diagnosed as abnormal in Preimplantation Genetic Diagnosis (PGD) cycles are useful for the establishment of human Embryonic Stem Cells (hESC) lines with genetic disorders. These lines can be helpful for drug screening and for the development of new treatments. Vitrification has proved to be an efficient method to preserve human blastocysts. One hundred and three abnormal or undiagnosed vitrified blastocysts from the PGD programme at Institut Universitari Dexeus were donated for human embryonic stem cell derivation. The overall survival rate after warming was 70.6 %. Our results showed better survival rates when blastocysts have not started the hatching process (initial/expanded 87.8 %, hatching 68.3 % and hatched 27.3 %). Thirty-five blastocysts and 12 partially surviving embryos were seeded. One hESC line with the multiple exostoses type 2 paternal mutation was obtained.

A critical appraisal of cryopreservation (slow cooling versus vitrification) of human oocytes and embryos

BACKGROUND

Vitrification is now a commonly applied technique for cryopreservation in assisted reproductive technology (ART) replacing, in many cases, conventional slow cooling methodology. This review examines evidence relevant to comparison of the two approaches applied to human oocytes and embryos at different developmental stages.

METHODS

Critical review of the published literature using PubMed with particular emphasis on studies which include data on survival and implantation rates, data from fresh control groups and evaluation of the two approaches in a single setting.

RESULTS

Slow cooling is associated with lower survival rates and compromised development relative to vitrification when applied to metaphase II (MII) oocytes, although the vitrification results have predominantly been obtained using direct contact with liquid nitrogen and there is some evidence that optimal protocols for slow cooling of MII oocytes are yet to be established. There are no prospective randomized controlled trials (RCTs) which support the use of either technique with pronuclear oocytes although vitrification has become the method of choice. Optimal slow cooling, using modifications of traditional methodology, and vitrification can result in high survival rates of early embryos, which implant at the same rate as equivalent fresh counterparts. Many studies report high survival and implantation rates following vitrification of blastocysts. Although slow cooling of blastocysts has been reported to be inferior in some studies, others comparing the two approaches in the same clinical setting have demonstrated comparable results. The variation in the extent of embryo selection applied in studies can lead to apparent differences in clinical efficiency, which may not be significant if expressed on a 'per oocyte used' basis.

CONCLUSIONS

Available evidence suggests that vitrification is the current method of choice when cryopreserving MII oocytes. Early cleavage stage embryos can be cryopreserved with equal success using slow cooling and vitrification. Successful blastocyst cryopreservation may be more consistently achieved with vitrification but optimal slow cooling can produce similar results. There are key limitations associated with the available evidence base, including a paucity of RCTs, limited reporting of live birth outcomes and limited reporting of detail which would allow assessment of the impact of differences in female age. While vitrification has a clear role in ART, we support continued research to establish optimal slow cooling methods which may assist in alleviating concerns over safety issues, such as storage, transport and the use of very high cryoprotectant concentrations.

Successful pregnancy in vitrified/warmed blastocyst intrafallopian transfer

OBJECTIVE

To analyze whether the use of blastocyst intrafallopian transfer is a feasible option in a case of repeated difficult ET.

DESIGN

Case report.

SETTING

Public hospital.

PATIENT(S)

Forty-year old nulliparous patient.

INTERVENTION(S)

Transfer of two vitrified/warmed blastocysts into the right tube by means of laparoscopy.

MAIN OUTCOME MEASURE(S)

Successful ET, clinical pregnancy.

RESULT(S)

Successful ET procedure resulting in positive ß-hCG and clinical pregnancy.

CONCLUSION(S)

In cases of repeated difficult ETs (regardless of whether the patient shows cervical adhesions or any type of genital malformations), blastocyst intrafallopian transfer can be a successful alternative approach.