RESUMEN
OBJECTIVE: To compare two different blastocyst biopsy protocols. DESIGN: Retrospective single-center cohort study. SETTINGS: Private in vitro fertilization center. PATIENT(S): The study included 1,670 frozen-thawed embryo transfers (FETs) with preimplantation genetic testing for aneuploidy (PGT-A). INTERVENTION: None. MAIN OUTCOME MEASURE(S): Survival rate (SR) after thawing, clinical pregnancy rate (CPR), ongoing implantation rate (IR), and live birth rate (LBR). RESULT(S): Eight hundred thirty-five FETs with PGT-A cycles including only embryos biopsied in the sequential blastocyst hatching and biopsy protocol paired with the ablation of one-fourth of the zona pellucida (ZP) were matched with 835 FETs with PGT-A cycles including only embryos biopsied in the day 3 prehatching protocol by female age (±1 year), number of embryos transferred, use of gestational carrier or egg donor, and day of blastocyst transfer. Only FETs with euploid blastocysts graded no lower than 4BB were included, and cycles with fewer than five oocytes were excluded. SR after thawing, CPR, ongoing IR, and LBR were significantly higher in the FET cycles with the embryos biopsied in the sequential hatching and biopsy protocol. Four cases of monozygotic twin pregnancies were reported with the day 3 prehatching protocol and none with the sequential hatching and biopsy protocol. CONCLUSION(S): Our results show, for the first time, that using different blastocyst biopsy protocols can affect clinical outcomes. Because the study was retrospective, our findings should be validated in a prospective trial.