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PurposeTo investigate whether embryo rebiopsy increases the yield of in vitro fertilization (IVF) cycles.MethodsRetrospective study including 18,028 blastocysts submitted for trophectoderm biopsy and preimplantation genetic testing for aneuploidy (PGT-A) between January 2016 and December 2021 in a private IVF center. Out of the 517 embryos categorized as inconclusive, 400 survived intact to the warming procedure, re-expanded, and were suitable for rebiopsy. Of them, 71 rebiopsied blastocysts were transferred. Factors affecting the probability of obtaining an undiagnosed blastocyst and clinical outcomes from blastocysts biopsied once and twice were investigated.ResultsThe overall diagnostic rate was 97.1%, with 517 blastocysts receiving inconclusive reports. Several blastocyst and laboratory features, such as the day of the biopsy, the stage of development, and the biopsy methodology, were related to the risk of obtaining an inconclusive diagnosis after PGT-A. A successful diagnosis was obtained in 384 of the rebiopsied blastocysts, 238 of which were chromosomally transferable. A total of 71 rebiopsied blastocysts were transferred, resulting in 32 clinical pregnancies [(clinical pregnancy rate (CPR)=45.1%], 16 miscarriages [(miscarriage rate (MR)=41%], and, until September 2020, 12 live births [(live birth rate (LBR)=23.1%]. A significantly lower LBR and higher MR were obtained after transferring rebiopsied blastocysts compared to those biopsied once.ConclusionAlthough an extra round of biopsy and vitrification may cause a detrimental effect on embryo viability, re-analyzing the test-failure blastocysts contributes to increasing the number of euploid blastocysts available for transfer and the LBR.

Purpose This study aimed to determine whether the new formulation of vitrification solutions containing a combination of hydroxypropyl cellulose (HPC) and trehalose does not affect outcomes in comparison with using conventional solutions made of serum substitute supplement (SSS) and sucrose. Methods Ovum donation cycles were retrospectively compared regarding the solution used for vitrification and warming of human oocytes. The analysis included 218 cycles ( N  = 2532 oocytes) in the study group (HPC + trehalose) and 214 cycles ( N  = 2353 oocytes) in the control group (SSS + sucrose). Results No statistical differences were found in ovarian stimulation parameters and baseline characteristics of donors and recipients. The survival rate was 91.3 % (95 % confidence interval (CI) = 89.8–92.9) in the HPC + trehalose group vs. 92.1 % (95 % CI = 90.4–93.7) in the SSS + sucrose group (NS). The implantation rate (42.8 %, 95 % CI = 37.7–47.9 vs. 41.2 %, 95 % CI = 36.0–46.4), clinical pregnancy rate (CPR) per transfer (60.7 %, 95 % CI = 53.9–67.5 vs. 56.4 %, 95 % CI = 49.3–63.5), and ongoing pregnancy rate (OPR) per transfer (48.5 %, 95 % CI = 41.5–55.5 vs. 46.3 %, 95 % CI = 39.2–53.4) were similar for patients who received either HPC + trehalose-vitrified oocytes or SSS + sucrose-vitrified oocytes. Statistical differences were found when analyzing blastocyst rate both per injected oocyte (30.2 %, 95 % CI = 28.3–32.1 vs. 24.1 %, 95 % CI = 22.3–25.9) and per fertilized oocyte (40.8 %, 95 %CI = 38.5–43.1 vs. 33.2 %, 95 % CI = 30.8–35.5) ( P  < 0.0001). Delivery rate was comparable between groups (37.2 %, 95 % CI = 30.8–46.6 vs. 36.9 %, 95 % CI = 30.4–43.4; NS). Conclusions Our data demonstrate that HPC and trehalose are suitable and safe substitutes for serum and sucrose. Therefore, the new commercial media can be used efficiently in the vitrification of human oocytes avoiding viral and endotoxin contamination risk.