Case report: two successful pregnancies following the transfer of re-vitrified human day 7 blastocysts developed from vitrified cleaved embryos

Short-term storage of tripronucleated human embryos

PURPOSE

To determine the survival and subsequent in vitro development of human cleavage stage embryos and hatched blastocysts following varying periods of short-term storage at 4 °C, using tripronucleated human embryos (TPN) as a model.

METHODS

TPN cleavage embryos and hatched blastocysts short-term stored at 4 °C for 0 h (control), 24 h and 48 h. The main outcome measures were: survival rates (SR) and in vitro developmental ability (blastocyst rate and blastocyst-re-expansion rate) in each of the groups after storage.

RESULTS

Cleavage-stage TPN survived at comparable rates to controls, regardless of storage time (average: 97.3 %). The in vitro development of cleavage-stage TPN stored for 24 h was comparable to that of controls (average 64.7 %), but was significantly impaired when storage lasted 48-h (20.8 %). After artificial shrinkage, SR was comparable in 24-h-stored and non-stored hatched blastocysts (85.7 %; p > 0.05), but was significantly impaired in the 48-h-stored group (20.0 %). Following 24-h storage, the re-expansion rate of hatched blastocysts was similar to that of controls (average: 57.1 %; p > 0.05), but was higher than that of the 48-h-stored group (15.0 %; p < 0.05).

CONCLUSIONS

TPN human cleavage embryos and blastocysts can be successfully stored short-term for up to 24 h at 4 °C without using cryoprotectants without any significant negative impact on survival or subsequent in vitro development.

Selection and vitrification of embryos with a poor morphological score: a proposal to avoid embryo wastage

Embryos with a poor morphological score at cleavage stage are usually discarded because they are considered unsuitable for transfer and cryopreservation. This study examined the in vitro blastocyst development after extended culture of these embryos and the clinical outcomes after transfer of these blastocysts in warming cycles. A total of 597 blastocysts (24.7%) were obtained from 2421 embryos with low morphological scores after extended culture. One hundred and sixty blastocysts (6.6%) with optimal morphology were vitrified. Embryo utilization rate was increased from 30.8% to 32.6%. After warming, 61 out of 92 blastocysts (66.3%) survived and were transferred in 44 cycles. The clinical pregnancy rate and the implantation rate were 40.9% (18/44) and 32.8% (20/61) respectively. Thirteen healthy babies were born, and 5 pregnancies aborted spontaneously. Our study suggested that some blastocysts derived from embryos with a poor morphological score can be successfully vitrified and give rise to live births. Selection and vitrification of viable embryos after extended culture of embryos with a poor morphological score may constitute a proposal to avoid embryo wastage.

Successful pregnancy following the transfer of vitrified blastocyst which developed from poor quality embryos on day 3

BACKGROUND

The selection of pre-embryos for transferred is based on morphological appearance. But some poor quality cleaved embryos also can be cultured to the blastocyst stage and implanted.

OBJECTIVE

To assess the clinical pregnancy outcomes of blastocyst transfer which developed from poor quality embryos.

MATERIALS AND METHODS

A total of 109 cleaved embryos with poor quality were cultured to day 5/day 6 and 27 (24.8%) blastocysts were collected from the 15 cycles/patients undergoing conventional IVF. All the blastocysts were cooling with fast-freezing. Then the blastocysts were warmed for transfer.

RESULTS

All of 25 vitrified blastocysts (92.6%) survived after warming and were transferred to 15 patients. Five of the women became pregnant.

CONCLUSION

Our results suggest that vitrified human day 5/day 6 blastocyst transfer which develop from poor quality embryo at day 3 can contribute to increasing cumulative pregnancy rates in assisted reproduction.

Live birth after anonymous donation of twice-cryopreserved embryos that had been stored in liquid nitrogen for a cumulative storage time of approximately 13.5 years

OBJECTIVE

To report a live birth after transfer of anonymously donated, twice-cryopreserved embryos that had been stored in liquid nitrogen for approximately 13.5 years.

DESIGN

Case report.

SETTING

A private assisted reproduction center.

PATIENT(S)

A 44-year-old recipient of donated cryopreserved embryos.

INTERVENTION(S)

Anonymous donation of cryopreserved blastocysts for procreation.

MAIN OUTCOME MEASURE(S)

Live birth after thawing and replacement of re-cryopreserved blastocysts.

RESULT(S)

Fourteen pronuclear-stage embryos and four cleavage-stage embryos were cryopreserved during a primary IVF cycle. In two separate cycles, one cycle for the primary patient and a subsequent cycle for the first embryo donor recipient, the 18 embryos were thawed and grown to the blastocyst stage for transfer. Supernumerary blastocysts (n = 5) not replaced at either of these two thaw cycles were re-cryopreserved and subsequently donated to another embryo donor recipient. Five blastocysts survived the thaw and three were transferred, resulting in a live birth. The embryos were cryopreserved for a cumulative storage time of approximately 4,909 days (13.4 years).

CONCLUSION(S)

The longevity (viability) of cryopreserved embryos maintained in liquid nitrogen remains to be determined; cryopreserved embryo donation for procreation should not be overlooked, regardless of the length of time that embryos remain in cryostorage.

Impact of the size of zona pellucida thinning area on vitrified-warmed cleavage-stage embryo transfers: a prospective, randomized study

PURPOSE

The aim of this study was to determine if the size of zona pellucida thinning area by laser assisted hatching could affect the rates of pregnancy and implantation for vitrified-warmed embryo transfers at the cleavage-stage.

METHODS

A total of 120 vitrified-warmed cleavage-stage embryo transfers were randomly assigned to either quarter or half of zona pellucida thinning group.

RESULTS

The rates of clinical pregnancy (46.7 versus 25.0%) and implantation (32.0 versus 16.2%) were significantly greater in the half thinning group than in the quarter thinning group (P = 0.0218 and P = 0.0090, respectively).

CONCLUSIONS

The results of this investigation show that, in vitrified-warmed embryo transfers at the cleavage-stage, the size of zona pellucida thinning area by laser assisted hatching impacts the rate of clinical pregnancy and implantation and that half of zona pellucida thinning significantly increases both of these results compared with quarter of zona pellucida thinning.

Case report: successful delivery following the transfer of a human re-vitrified day-7 spontaneously hatched blastocyst developed from vitrified cleaved embryos

PURPOSE

To report a successful delivery after the transfer of a re-cryopreserved day-7 hatched blastocyst.

METHODS AND RESULTS

A 30-year-old woman underwent a long-treatment protocol for ovarian stimulation. Fourteen mature oocytes were obtained, and twelve were fertilized. On day 3, two cleaved embryos were transferred, but no implantation occurred. The remaining embryos were vitrified. Subsequently, two vitrified day-3 embryos were transferred. The woman became pregnant and delivered a healthy baby. Subsequently, two vitrified day-3 embryos were transferred, but no pregnancy occurred. Subsequently, all the remaining vitrified day-3 embryos were cultured. On day 5, no blastocyst was obtained. The remaining embryos were continued to be cultured. On day 7, a hatched blastocyst was obtained and re-vitrified. Subsequently, the re-vitrified day-7 hatched blastocyst was transferred. The woman became pregnant and delivered a healthy female.

CONCLUSIONS

The day-7 hatched blastocyst developed from vitrified embryos can be re-vitrified and have pregnancy potential after re-warming.