Mapping the evidence and research gaps on preimplantation genetic testing for aneuploidy in recurrent implantation failure: a scoping review.

BACKGROUND: Recurrent implantation failure (RIF) represents a complex and heterogeneous condition in assisted reproductive technology (ART), characterized by unclear etiology and limited evidence-based management strategies. Preimplantation genetic testing for aneuploidy (PGT-A) has been proposed to improve reproductive outcomes through selection of euploid embryos; however, its clinical utility in RIF remains controversial. METHODS: A scoping review was conducted to systematically map the available evidence regarding the role of PGT-A in RIF. A comprehensive literature search identified 18 studies evaluating reproductive outcomes in RIF patients undergoing PGT-A compared with conventional in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI). Data were extracted and narratively synthesized across key outcomes, including implantation rate (IR), clinical pregnancy rate (CPR), live birth rate (LBR), and miscarriage rate (MR). Methodological quality was assessed using the Newcastle-Ottawa Scale (NOS), and sources of heterogeneity, including variability in RIF definitions, PGT-A methodologies, and patient subgroups, were also explored. RESULTS: Several studies reported improved outcomes at the level of individual embryo transfer (ET), including higher IR, CPR, and LBR per transfer following PGT-A. However, these findings were not consistently observed when outcomes were assessed at the patient level. In particular, cumulative live birth rate (CLBR) was generally comparable between PGT-A and non-PGT-A groups, especially in unexplained - uRIF or idiopathic - iRIF populations. Similarly, MR was largely unchanged across studies despite improved embryo selection. Subgroup analyses suggested that PGT-A may provide greater benefit in patients with a higher likelihood of embryo-related implantation failure (IF), such as those of advanced maternal age (AMA), whereas limited benefit was observed in uRIF/iRIF cohorts. Overall, substantial heterogeneity was identified regarding RIF definitions, laboratory methodologies, and clinical protocols. CONCLUSIONS: The available evidence suggests that PGT-A may improve treatment efficiency by increasing the probability of success per ET in selected RIF populations. Nevertheless, it does not consistently improve CLBR or reduce miscarriage risk, underscoring the multifactorial nature of IF. Consequently, PGT-A should be considered within an individualized treatment strategy rather than as a universal intervention for all RIF patients. Further prospective studies using standardized definitions and protocols are required to better define its clinical role.