JBRA Assisted Reproduction 2025;29(Suppl.2 SBRA 2025):203
Poster Presentation
29^th Annual Congress of the SBRA. São Paulo/SP - Brazil, 2025
doi: 10.5935/1518-0557.20263882

P-191. Rebiopsy of Embryos Initially Diagnosed as Aneuploid Re veals a Significant Rate of Usable Embryos

Gustavo Nardini Cecchino¹, Rafael Portela¹, Juliana Halley Hatty¹, Rodrigo da Rosa Filho¹

¹ Mater Prime - Mater Lab - São Paulo – SP – Brasil

Objective: To evaluate the diagnostic reproducibility between two independent PGT genetic laboratories by rebiopsying embryos initially diagnosed as aneuploid and deemed non-transferable.
Methods: This retrospective study included 56 blastocyst-stage embryos from 16 patients who underwent in vitro fertilization (IVF) with preimplantation genetic testing for aneuploidy (PGT-A) between 2022 and 2025. Patient ages ranged from 33 to 45 years (median: 41 years). Initially, all embryos were biopsied and analyzed by Clinical Laboratory A using the ReproSeq NGS assay which diagnosed 56 embryos as aneuploid. None were considered suitable for clinical transfer. Patients were recontacted in 2024 and counseled about a new clinically validated assay and offered a clinical rebiopsy. All 56 embryos were subsequently rebiopsied by the same embryologist and analyzed by Laboratory B, which employed a distinct clinically validated genetic testing platform using the PGTSeq NGS assay for independent blinded clinical embryo assessment. Embryos were clinically classified as negative or positive for whole chromosome or segmental aneuploidy with the opt-in option to report segmental and whole chromosome mosaicism. Results were compared to assess inter-laboratory embryo diagnostic concordance and the potential recovery of transferable embryos
Results: Among the 56 embryos originally classified as whole chromosome aneuploid or chaotic by Laboratory A, 6 embryos (~10.7%) were reclassified by Laboratory B as negative for whole chromosome aneuploidy, segmental aneuploidy, and normal diploid. 40 matched the same chromosome abnormalities (40/56 ~%71) and 10 (10/56 ~17%) partially matched with some full chromosome aneuploid confirmed by not all. All biopsies were performed by the same embryologist, with no relevant variation in technique that could explain the observed discrepancies. The discordance highlights inter-laboratory variability in the PGT assays, interpretation, and threshold settings for genetic diagnosis.
Conclusion: A significant proportion of embryos initially deemed fully aneuploid and unsuitable for transfer were reclassified as clinically usable following rebiopsy and analysis by a clinically validated assay and evidence-based reporting by an independent laboratory. These findings raise concerns about inter-laboratory variability in PGT-A diagnostics and underscore the risk of discarding viable embryos due to technical or interpretive inconsistencies. Reliable laboratory protocols, validated technologies, and consistent classification criteria are essential to maximize embryo utilization and improve clinical outcomes. Further multicenter studies are warranted to promote standardization in PGT-A assay validations, reporting thresholds and biopsy practices, and caution should be considered before discarding embryos reported abnormal.