Repeated Implantation Failure (RIF) means that at least 3 previous IVF attempts with embryo transfer and good embryo quality have failed to implant. This is extremely frustrating for both patients and their reproductive health care providers and is one of the biggest challenges of in vitro fertilization (IVF). Some causes are known (e.g. smoking, obesity, severely reduced quality of eggs and sperm, thrombophilia, other factors affecting the uterus and fallopian tubes), but very often the cause is unknown.
Recent meta-analyses (scientific publications that use statistical methods and compare different studies with the same question) by Busnelli et al (2021) and Yang et al (2019) have evaluated PBMC (Peripheral Blood Mononuclear Cell) administration as one of the most promising methods for RIF. The clinical pregnancy rate, embryo implantation rate and live birth rate were significantly higher in the proportion of individuals who received PBMC flushing a few days before the embryo was placed in the uterus. This positive effect could be demonstrated in the group that had 3 or more implantation failures in the past.