ABSTRACT
Introduction According to large registries, nearly 30% of in vitro fertilisation (IVF)/intracytoplasmic sperm injection (ICSI) cycles performed in both Europe and the US result in pregnancy, the rate being as high as 50-60% in patients with a very good prognosis being treated at highly successful units.1 However, even in these units, embryos from some patients repeatedly fail to implant, a condition which has been termed repeated implantation failure (RIF). There is no clear definition of RIF. For some groups it is an unsuccessful patient with more than ten good quality embryos transferred in subsequent cycles.2,3 This definition may seem too loose, according to the actual method of practice. Thus, we can consider that if a patient has undergone three good quality embryo transfers if she is <37 years old, or two good quality embryo transfers if she is ≥37 years old, without achieving a pregnancy, extended investigation is required (Fig 29.1). If an embryo fails to implant, it may be due to
decreased endometrial receptivity, embryonic factors, and thus, gamete factors, and/or systemic maternal conditions (Table 29.1).
