JBRA Assisted Reproduction 2025;29(Suppl.2 SBRA 2025):1
Oral Presentation
29^th Annual Congress of the SBRA. São Paulo/SP - Brazil, 2025
doi: 10.5935/1518-0557.20263515

O-01. Blastocyst Collapse Per Se Is Not Predictive of Aneuploidy: A Critical Appraisal Using Morphodynamic Stratification

Tulius Augustus Ferreira Freitas¹, Eduardo Gomes Sá¹, Hamilton de Martin¹, Ellayne Cavalcanti Queiroz¹, Andrea Mesquita Lima¹, Gleicyane Sousa Santos Alam¹, Renata Reis Pimentel Castro¹, Fabio Eugênio Magalhães Rodrigues¹, Eduardo Paula Miranda¹, Sebastião Evangelista Torquato¹

¹ Bios Centro de Medicina Reprodutiva - Fortaleza - CE - Brasil

Objective: Spontaneous blastocyst collapse events observed via time-lapse imaging have been proposed as non-invasive markers of chromosomal instability. However, the predictive value of collapse in isolation remains controversial. This study aimed to determine whether blastocyst collapse is independently associated with aneuploidy, or whether this association is mediated by morphodynamic features related to embryo structural integrity, particularly fragmentation of the inner cell mass (ICM) and trophectoderm (TE).
Methods: This retrospective cohort study included 1,182 embryos cultured individually in time-lapse incubators and biopsied for PGT-A between September 2022 and December 2024 at a private IVF center. Spontaneous collapse events were categorized as minor (CL) when partial detachment of the TE from the zona pellucida occurred, and as major (MCL) when complete detachment was observed. The frequency of each type of collapse per embryo was recorded. Embryos were also stratified using the Blastocyst Fragmentation Indicator (BFI), classifying them as NN (no fragmentation), FN (fragmentation of ICM only), or FF (fragmentation of both ICM and TE). Poisson generalized linear models and logistic regression were used to assess associations between collapse events, BFI, and aneuploidy, including interaction terms.
Results: Aneuploid embryos presented significantly more minor collapses than euploid ones (mean CL: 1.74 vs. 1.02; OR = 0.454; p < 0.001). However, this association became non-significant when BFI was included in the model (p = 0.565), while BFI remained a strong predictor of collapse frequency (p<0.001). No interaction was found between aneuploidy and fragmentation status (p=0.936), indicating that the observed relationship between collapse and chromosomal abnormality is mediated—not moderated—by structural fragmentation. Embryos with FF profiles showed the highest collapse rates (CL = 3.01; MCL = 1.42), while NN embryos exhibited low collapse activity (CL = 0.89; MCL = 0.24; p<0.001 for all comparisons). Importantly, a subset of euploid embryos exhibited collapse events, including both minor and major collapses, despite presenting no detectable ICM or TE fragmentation (BFI = NN).
Conclusion: Our findings challenge the use of blastocyst collapse as an independent non-invasive marker of aneuploidy. Although statistically associated with chromosomal errors, this link is lost when structural fragmentation is considered, suggesting that collapse reflects—but does not determine—embryo viability. Importantly, collapse events were frequently observed in viable, euploid embryos that retained structural integrity, particularly in younger patients. Therefore, collapse per se lacks specificity and should not be used in isolation for embryo selection or deselection. Clinical interpretation of collapse dynamics must consider concurrent morphodynamic parameters, particularly those related to structural fragmentation. These results indicate the need for a multidimensional approach in time-lapse–based embryo evaluation, integrating dynamic and morphological criteria to improve the accuracy of embryo ranking, particularly for deselection purposes.