FERTILITY, IVF AND REPRODUCTIVE GENETICS: Edited by Emre Seli and Juan A. García VelascoDetermining diagnostic criteria and cause of recurrent implantation failureCakiroglu, Yigita,b; Tiras, Bulenta,bAuthor Information aAcibadem Maslak Hospital Assisted Reproductive Techniques Unit bAcibadem Mehmet Ali Aydinlar University, Istanbul, Turkey Correspondence to Yigit Cakiroglu, Acibadem Maslak Hospital Assisted Reproductive Techniques Unit, Darussafaka, Buyukdere Cad. No: 40 34457 Sariyer, Istanbul 34457, Turkey. Tel: +90 532 585 65 88; e-mail: email@example.com Current Opinion in Obstetrics and Gynecology: June 2020 - Volume 32 - Issue 3 - p 198-204 doi: 10.1097/GCO.0000000000000620 Buy Metrics Abstract Purpose of review Recurrent implantation failure (RIF) refers to the absence of implantation after repeated transfer of good embryos into a normal uterus. This review discusses the diagnostic criteria and cause of RIF. Recent findings Regardless of the advancements in IVF practice, RIF is still a challenge that has to be solved. Exact definition of RIF is lacking today. For the initial evaluation, a rigorous algorithmic evaluation should be compromised with an individualized principle. Factors that might affect the number and quality of the oocyte and sperm cells should be investigated in order to obtain a good-quality embryo. Embryo assessment should be performed under ideal laboratory circumstances. The uterine environment should be carefully evaluated and the embryo should be transferred into the uterus at the most receptive time. Some of the newly introduced diseases and empirical treatment strategies, such as chronic endometritis, vaginal microbiota, immunologic profile and immunomodulator treatments, can be discussed with the couple under the light of adequate evidence-based information. Summary New diagnostic and treatment modalities are needed to be introduced, which would be safe, efficient and efficacious after well-designed randomized controlled trials. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.