Impact Of Blastocyst Re-Biopsy And Re-Freeze On Pregnancy Outcomes: A Systematic Review And Meta-Analysis.

While blastocyst vitrification and biopsy are generally considered safe, it is unclear if multiple biopsies and vitrification-warming procedures negatively impact clinical outcomes. This situation arises when patients request preimplantation genetic testing (PGT) on already cryopreserved embryos. Another scenario necessitating additional vitrification-warming procedures is failure to obtain a result from the initial trophectoderm biopsy, in which case a second biopsy would also be necessary. There is very limited information on the clinical outcomes following transfers of blastocysts twice biopsied and vitrified-warmed. The objective of this study was to compile the available literature on the clinical pregnancy (CP) rates of blastocysts transferred after undergoing multiple vitrification-warming and/or biopsy procedures. Systematic review and meta-analysis. A systematic search of the literature was conducted using the PubMed database. Studies were selected for inclusion if they compared blastocysts 1) biopsied and vitrified-warmed once (1Bx + 1V/W), 2) biopsied once but vitrified-warmed twice (1Bx + 2V/W), and/or 3) biopsied and vitrified-warmed twice (2Bx + 2V/W). A total of six retrospective cohort studies met inclusion criteria. Data involving patient and blastocyst characteristics, PGT results, and clinical outcomes were extracted. Study quality was assessed using the Newcastle Ottawa scale for non-randomized comparative cohort studies. The studies were evaluated independently by two of the authors and any discrepancies were settled by a third author. From the six studies included, a multiple-treatments random-effects meta-analysis comparing the risk difference in CP rate for the three groups identified above was performed. A total of 9437 single euploid blastocyst transfers were included in the analysis. The pooled CP rate was significantly lower in the 2Bx + 2V/W group compared to the 1Bx + 1V/W group, with an estimated difference of 13%, 95% CI [4.3-21.6%]. No significant differences in CP rate were observed between the 1Bx + 1V/W and 1Bx + 2V/W groups (risk difference, 4.5%; 95% CI [-2.1-11.1%]) or between the 1Bx + 2V/W and 2Bx + 2V/W groups (risk difference, 8.5%; 95% CI [-2.3-19.3%]). These findings indicate that CP rates are significantly reduced when blastocysts are biopsied and vitrified-warmed twice compared with blastocysts biopsied and vitrified-warmed once. For patients who receive an inconclusive diagnosis from the initial biopsy, this risk should be weighed against the risk of transferring a possible aneuploid embryo. However, given the retrospective nature of the limited number of studies available, further research is needed to confirm this finding.