Outcomes of embryo vitrification at different developmental stages

Abstract

Introduction: Advances in cell culture media have led to a shift from cleavage stage embryo transfer to blastocyst stage transfer. Extended embryo culture to the blastocyst stage provides some theoretical advantages and disadvantages. There has been controversy. This study is sought to evaluate the clinical outcomes of vitrified-warmed cleavage-stage and blastocyst-stage embryo transfers in patients undergoing Artificial Reproductive Technique treatments.Material and method: The study was performed on 2740 women undergoing frozen embryo thawing transfer. Patients' basic situation, status of frozen embryo transfer cycle, clinical pregnancy rate, early abortion rate, sex ratio of birth, and birth weight were retrospectively analyzed. We compared the main clinical results of recovery of frozen embryo on the cleavage stage and blastocyst stage. Furthermore, we evaluated the clinical outcomes of blastocyst cryopreservation on Day 5, 6, or 7 after oocyte retrieval according to the day of blastocyst expansion were evaluated.Results: The implantation ratio of cleavage stage embryos was 21.62% compared with 43.52% on D5 (P < .05). The D5, D6, and D7 implanting rates were statistically different. The pregnancy rates were 57.56%, 51.76%, and 35.95% versus 37.79%, respectively for embryos cryopreserved on D5, D6, D7, and D3. The ectopic pregnancy rate and early abortion rate were statistically different between D5 and D3. The sex ratio, the birth weight, and birth defect were not statistically different among the four groups.Conclusions: Blastocyst transfer achieved a higher implantation rate than vitrified cleavage stage embryo and decreased ectopic pregnancy rate. With increased incubation days before expansion blastocyst formed, the implantation rate is reduced and the early abortion rate increases.

In vitro fertilization outcomes of frozen-thawed embryo transfer are better with hatched blastocysts than with hatching blastocysts

“…Blastocysts are preimplantation embryos that successfully pass the critical step of genomic activation and have a high developmental potential [12,18]. Furthermore, blastocyst transfer is more physiologically appropriate because it is closer to the time of natural implantation and may improve the synchronization of the endometrium and embryo development [18,20,21].…”

“…With gradual developments in technology and preimplantation embryo culture, the number of blastocyst transfers has continuously increased [13]. Many studies have demonstrated the theoretical advantages of blastocyst transplantation, indicating a better correlation between morphology and aneuploidy, better synchronization with endometrium, and increased implantation potential [12,13,17,18]. Blastocyst transfer has become more common globally; however, selecting the best embryos from blastocysts is necessary.…”

“…In a recent study [12], blastocyst stage ET achieved higher implantation rates than did cleavage stage embryos in FET. Moreover, the clinical outcomes of different blastocyst developmental stages at the time of ET have been compared to elucidate success rates.…”

Innovations for Optimizing Fertility and Ovarian Functionality in Female Cancer Patients

“…47 Vitrification protocols have also been improved, and usually a mixture of ethylene glycol and dimethyl sulfoxide is applied as a cryoprotectant, in association with an extracellular cryoprotectant, such as sucrose. 48 Choosing the cryopreservation method is crucial because the ability of the embryo to survive reflects in the implantation ability. Commonly, to perform the transfer after the cryopreserved embryo is thawed/warmed, patients showing a natural ovulatory cycle do not need further hormonal manipulation.…”

“…49,50 In addition, patients with a thin endometrial wall, or other complications, such as prolonged menstruation and bleeding at ovulation are offered a treatment with ethinyl and/or progesterone. 48 For the transfer, embryos are deposited in the uterus through a catheter, in the lower to mid portion. 51 Analgesia or anesthesia is not mandatory for performing transcervical embryo transfer.…”