Impact of double versus single blastocyst biopsy and vitrification on clinical and neonatal outcomes in PGT cycles: A systematic review and meta‐analysis of embryo retesting

Introduction As PGT advances in assisted reproduction, more embryos with inconclusive results, yet potentially transferable, have emerged. Current studies reveal a disparity between the reproductive potential of retested blastocysts and the supporting evidence. This systematic review and meta‐analysis compared clinical outcomes of rebiopsied and revitrified blastocysts with those biopsied and vitrified once. Material and Methods Searches were conducted on June 26, 2024, across PubMed, EMBASE, Cochrane Library, Scopus, Web of Science, and Google Scholar, using thesaurus and free‐text terms. Selection, data extraction, and risk of bias were assessed by three independent reviewers. The primary outcomes were live birth rate (LBR) and singleton birthweight; secondary outcomes were clinical pregnancy rate (CPR), clinical pregnancy loss rate (CPLR), positive pregnancy rate, very early pregnancy loss rate, and neonatal outcomes. Quantitative analyzes were performed using a random‐effects model, pooling dichotomous outcomes as odds ratios (OR) and 95% CI and continuous outcomes as mean differences (MD) using the inverse variance model. Subgroup analyses based on “biopsy day” and “morphological grades” were performed. Results Seventeen studies were included, reporting 36,441 SET cycles. Very low‐quality evidence suggests that rebiopsy and revitrification were associated with a decreased likelihood of LBR compared with single biopsy and vitrification (OR = 0.54, 95% CI = 0.44–0.67; I 2 = 12%; p < 0.00001, Pred Int = 0.38–0.79; 13 studies). No effect of retesting was found on the birthweight of 141 newborns (MD = 21.05, 95% CI = −64.83–106.94; I 2 = 0%; p = 0.63, six studies). The odds of pregnancy were decreased for both positive pregnancy (OR = 0.58, Pred Int = 0.30–1.12; I 2 = 41%; p = 0.001, eight studies) and CPR (OR = 0.60, 95% CI = 0.51–0.70; I 2 = 0%; p < 0.00001, 14 studies), leading to a higher CPLR (OR = 1.56, 95% CI = 1.14–2.12; I 2 = 0%; p = 0.005, 13 studies). No statistically significant subgroup effects were detected; however, the “biopsy at D5” and “high‐quality” subgroups showed 10%–20% higher odds of LBR, which may hold clinical value and warrant further investigation. Conclusions Decision‐making on retesting embryos for PGT should be done with caution, as it might reduce live birth rate in order to obtain the precise genetic diagnosis. Larger and well‐designed studies, controlling for the main sources of bias, are still needed in order to improve the quality of the available evidence.