Evaluation of IL-1β and TNF-α level in endometrial flush in patients with recurrent implantation failure

Infertility is defined as the inability to conceive within a year of regular unprotected intercourse affecting one in six couples. The most common causes of infertility are ovulatory dysfunction, male factor infertility, and tubal disease [1]. Unexplained Infertility (UI) and Recurrent Implantation Failure (RIF) are diagnoses based on failed pregnancy attempts with current infertility treatment options. UI is diagnosed when testing is inconclusive and RIF is diagnosed after three failed In Vitro Fertilization (IVF) cycles. UI is the absence of conception despite 12 months of unprotected intercourse, not explained by anovulation, poor sperm quality, tubal pathology or other known cause of infertility. RIF is defined by three failed IVF cycles in which one or two high-quality embryos are transferred in each cycle or by two failures in oocyte donor recipients after the transfer of good quality embryos [1]. UI is a common cause of infertility affecting 10-30% of infertile couples [2], while RIF is present in around 10% of in vitro fertilization (IVF) cycles [3].