Immunological interventions in recurrent implantation failure: a systematic review and SWOT analysis

INTRODUCTION: Recurrent implantation failure (RIF) occurs when pregnancy is not achieved after multiple embryo transfers. The lack of standardized diagnostic criteria among clinicians makes RIF a particularly challenging condition, leading to the use of various procedures, including immunological ones, often without robust evidence. This study aims to provide an overview of the main characteristics of existing research on the role of interventions in relation to in vitro fertilization (IVF) outcomes in patients with RIF. EVIDENCE ACQUISITION: A comprehensive bibliographic search was systematically conducted from inception to November 2024, focusing on studies that evaluated the impact of immunological treatments in RIF cases, comparing IVF outcomes between case and control groups. EVIDENCE SYNTHESIS: A total of 77 studies were included. The diagnostic criteria for RIF were heterogeneous, with only 36 studies (47%) defining RIF as three or more failed embryo transfers. Moreover, the studies generally had small sample sizes. CONCLUSIONS: There is not yet sufficient evidence to support the routine use of immunological interventions in clinical practice for RIF. The existing research is marked by methodological inconsistencies, which limit the reliability and generalizability of the results.