Outcomes of blastocysts biopsied and vitrified once versus those cryopreserved twice for euploid blastocyst transfer

Abstract

Trophectoderm biopsy with comprehensive chromosome screening (CCS) has been shown to increase implantation and pregnancy rates. Some patients desire CCS on previously cryopreserved blastocysts, resulting in blastocysts that are thawed/warmed, biopsied, vitrified and then warmed again. The effect of two cryopreservation procedures and two thawing/warming procedures on outcomes has not been effectively studied. Cycles were divided into two groups: group 1 patients underwent a cryopreserved embryo transfer with euploid blastocysts that were vitrified and warmed once; group 2 patients had a cryopreserved embryo transfer of a euploid blastocyst that was cryopreserved, thawed/warmed, biopsied, vitrified and warmed. Groups 1 and 2 included 85 and 17 women aged 35.6 ± 3.9 and 35.3 ± 4.9 years, respectively (not significantly different). Blastocyst survival in group 1 (114/116, 98.3%) and survival of second warming in group 2 (21/24, 87.5%) was significantly different (P = 0.0354). There was no difference between biochemical (68.2% and 62.5%) and clinical (61.2% and 56.3%) pregnancy rates, implantation rate (58.4% and 52.4%) and live birth/ongoing pregnancy rate (54.0% and 47.6%) between groups 1 and 2, respectively. Although it is unconventional to thaw/warm, biopsy, revitrify and rewarm blastocysts for cryopreserved embryo transfer, the results indicate that outcomes are not compromised. Trophectoderm biopsy and screening the embryos for chromosomal abnormalities has been reported to increase implantation and pregnancy rates. There is a category of patients requesting chromosomal screening on previously cryopreserved blastocysts. This scenario requires blastocysts to be thawed/warmed, biopsied, cryopreserved, and thawed/warmed again. The effect of double cryopreservation procedures and double thawing/warming procedures on pregnancy is unknown. Patients were divided into two groups, group 1 underwent a cryopreserved embryo transfer with a chromosomally normal blastocyst that was vitrified and warmed once and group 2 included patients that had a cryopreserved embryo transfer of a chromosomally normal blastocyst that was cryopreserved, thawed/warmed, biopsied, vitrified, and rewarmed. A total of 85 and 17 women aged 35.6 ± 3.9 and 35.3 ± 4.9 years were included in groups 1 and 2, respectively. The survival rate for group 1 (114 of 116, 98.3%) compared with the second warming for group 2 (21 of 24, 87.5%) was significantly higher. There was no difference between biochemical (68.2% and 62.5%), and clinical pregnancies (61.2% and 56.3%), implantation (58.4% and 52.4%), and live birth/ongoing rates (54.0% and 47.6%) between groups 1 and 2. Although it is unconventional to twice cryopreserve and twice thaw/warm a blastocyst, our results indicate that outcomes are not compromised.

Preparation of endometrium for frozen embryo replacement cycles: a systematic review and meta-analysis

“…There has been a recent significant increase in the frozen embryo replacement (FER) cycles not only due to the availability of surplus embryos but also due to cryo-all cycles to avoid the risk of ovarian hyperstimulation syndrome [1], preimplantation genetic screening [2], and concerns for detrimental effect of controlled ovarian stimulation on endometrial receptivity in a fresh cycle [3]. The 2011 results, published in 2016, generated from European registers by ESHRE reported that the proportion of FER cycles was 32.3 % [4] compared to 28 % in 2010 [5].…”

Blastocysts can be rebiopsied for preimplantation genetic diagnosis and screening

“…Smith et al (15) reported a live birth after transfer of blastocysts that were frozen and thawed twice using a slow-freezing protocol. Taylor et al (7) recently demonstrated that previously cryopreserved blastocysts could be successfully warmed, biopsied, revitrified, and rewarmed, and the survival rate of rewarmed blastocysts was 87.5%. In our study, of the 19 twice-warmed blastocysts, 18 (94.7%) survived the second warming.…”

“…Wininger et al (6) reported a case of pregnancy after the blastocysts were rebiopsied following allele dropout after an initial biopsy at day 3. Most recently, Taylor et al (7) reported the rebiopsy of three test-failure blastocysts in two PGS cycles. After rewarming, two rebiopsied blastocysts survived but resulted in no pregnancy.…”

Quality control standards in PGD and PGS

“…The use of vitrification is being tested to determine if freezing all embryos in routine IVF 9 cycles gives a higher success rate, as it allows for optimization of the endometrium (Roque et al, 2015). These freeze-all cycles, open up the opportunity to freeze all embryos post biopsy for PGD (Schoolcraft et al, 2011, Taylor et al, 2014b. This relaxes the time constraints on the PGD team to perform the diagnosis and allows batching of samples, both of which make the test significantly cheaper and improves the quality of the test results.…”