Subtle Endometriosis and Unexplained Infertility

Unexplained infertility (UI) is a diagnosis of exclusion for infertile couples; within an otherwise asymptomatic patient with a normal clinical examination and ultrasound evaluation revealing no pelvic pathology, UI may be associated with undiagnosed pelvic diseases. We may speculate whether UI is really unexplained or if there are undocumented subtle pathological pelvic conditions that might interfere with the processes involved in natural fertilization. Subtle endometriosis may be related to various mechanisms involved in the different stages of fertilization, embryo development, and implantation, and there is speculation about its role in cases of UI. There is no consensus about whether milder stages of endometriosis are a cause of infertility or merely an incidental finding in some patients with UI. Studies by our group and others have shown that even cases of milder disease may inhibit mechanisms involved in conception, such as follicular steroidogenesis and oocyte competence. There appears to be an increase in oxidative stress (OS) markers in both the follicular and peritoneal compartments of patients with endometriosis as well as a possible increase in enzyme expression in cumulus granulosa cells (CC) which may alter oocyte development.