Correlation between embryological factors and pregnancy rate: development of an embryo score in a cryopreservation programme

Abstract

Purpose To establish which embryo parameters, in frozen thawed embryo transfers, have the highest prognosis value in the establishment of pregnancy. The relative importance of different embryo parameters is used to develop an embryo score. Methods Retrospective analysis of the implantation rate in 356 frozen/thawed single embryo transfers. A logistic regression model is used to establish an embryo score. Results A direct correlation is established between the implantation rate and fresh embryo development (number of blastomeres and their symmetry), survival rate after thawing and mitosis resumption after overnight culture.Conclusions An embryo score is developed to determine the implantation potential of frozen/thawed embryos.

Using the Society for Assisted Reproductive Technology Clinic Outcome System morphological measures to predict live birth after assisted reproductive technology

“…This is consistent with Racowsky et al (10) using SART data, and confirms the results of prior studies based on other data (19, 20). Symmetry was also a significant predictor in all four models in this study which is also consistent with prior work (21, 22). …”

Serum estradiol level on trigger day impacts clinical pregnancy rate in modified natural frozen embryo transfer cycles

“…The mean level of estradiol on the day a heartbeat could be detected of embryo and embryo quality at the time of freezing, 11,27-29 embryo damage after thawing, [29][30][31][32] presence of at least one good-quality embryo, 11 and use of embryos that have undergone further development after thawing at the time of embryo transfer. 29,33,34 A few studies assessed the prognostic factors for clinical outcomes after FET cycles with the vitrified-warmed method, and these demonstrated that women's age and ovarian hyperstimulation syndrome as reason for vitrification, 35 fewer previous ART treatment cycles, embryo transfer using at least one intact embryo, and embryo quality after warming 12 were significant prognostic factors.…”

“…After follow-up, the serum estradiol and progesterone levels on the day of embryo transfer were not predictive for clinical pregnancy and live births after vitrified-warmed embryo transfer in the natural cycle. In previous studies that evaluated the prognostic factors for pregnancy outcomes after FET cycles with slow-freezing protocols, the following variables were reported: women's age and BMI, 11,21,22 baseline antral follicle count and AMH level in the index stimulation cycle, 23 etiology of infertility, 24 type of fertilization methods, 25 number of previous pregnancies, 24 number of previous ART treatments, 24,25 presence of pregnancy in the fresh cycle, 8 of embryo and embryo quality at the time of freezing, 11,27-29 embryo damage after thawing, [29][30][31][32] presence of at least one good-quality embryo, 11 and use of embryos that have undergone further development after thawing at the time of embryo transfer. 29,33,34 A few studies assessed the prognostic factors for clinical outcomes after FET cycles with the vitrified-warmed method, and these demonstrated that women's age and ovarian hyperstimulation syndrome as reason for vitrification, 35 fewer previous ART treatment cycles, embryo transfer using at least one intact embryo, and embryo quality after warming 12 were significant prognostic factors.…”

Human Embryo Cryopreservation—Methods, Timing, and other Considerations for Optimizing an Embryo Cryopreservation Program

“…104,105 Cell stage, cell symmetry, cleavage pattern (synchronous versus asynchronous), and degree of fragmentation are embryo morphology characteristics shown to influence survival and implantation rates following slow freezing. 104,[106][107][108] The method of cryopreservation may be as important as the criteria used to determine survival as one or more of the embryo's blastomeres may lyse after thawing. 104,105 Embryos with 100% intact blastomeres will have a higher implantation rate than those that have a portion of their blastomeres lysed.…”

“…48 Similar results were reported for day 3 embryos that had 80% or more intact blastomeres, resulting in a 25% implantation rate for women younger than 35. 108 Efforts to improve slow freezing methods have included removal of lysed blastomeres and increasing the concentration of nonpermeating CPA sucrose to enhance blastomere dehydration and protection during rehydration. [111][112][113][114][115] Removal of lysed blastomeres has been proposed as a way to eliminate the potentially toxic effect of necrotic cells and physically eliminate obstacles that may interfere with adhe-sion and communication among surviving cells.…”