Immunology Updates in Recurrent Implantation Failure in In Vitro Fertilization

Purpose of ReviewTo summarize standards and recent advances in the understanding of immunology in recurrent implantation failure in IVF.Recent FindingsRecent consensus groups have put forth recommendations regarding the criteria for RIF. The focus of recent studies in RIF has shifted to more nuanced relationships of immunologic dysfunction at the maternal/fetal interface rather than systemic peripheral sources. Recent areas of novel therapy investigation include intrauterine PMBCs, PRP, and GCSF. Accumulating data on chronic endometritis suggests it may be associated with recurrent implantation failure and treatment may improve reproductive outcomes.SummaryRIF remains a frustrating and elusive diagnosis for patients and clinicians. In the era of improved IVF protocols and genetic screening, the true incidence of RIF is likely quite low. New recommendations for a consensus diagnosis for RIF may improve the generalizability of future studies. The contribution of immunologic factors in RIF has long been a focus of investigation, and prior therapies have focused on systemic immune suppression, without clear improvement in pregnancy rate and at high cost to patients. More recent studies have identified immune profiles at the maternal/fetal interface that may provide avenues for more targeted and effective therapies. Intrauterine PMBCs, PRP, and subcutaneous GCSF may offer some benefit in improving implantation rate, although data is preliminary and not yet proven for clinical practice. Chronic endometritis remains a potential contributor to RIF, although treatment and/or cure and its relationship to improved live birth rates remain debatable. Unproven therapies should continue to be avoided in this population.