Endometriosis and infertility: a cause-effect relationship?

Two major methodological problems that impact clinical research in endometriosis are the absence of a low-cost, highly reliable method for diagnosing endometriosis and the possibility that endometriosis is actually multiple different diseases that we have not yet been able to differentiate. Animal models of endometriosis clearly demonstrate that advanced endometriosis causes reduced fertility. In humans, endometriosis and infertility are commonly associated. However, few data from high-quality clinical trials demonstrate that endometriosis causes infertility in humans. Future research should focus on the implications of the observation that, in ovarian endometriosis cysts, the epithelium is monoclonal. This observation suggests that nonrandom somatic mutations cause ovarian endometriosis cysts. If somatic mutations cause ovarian endometriosis cysts, it is likely that a small number of genes can be identified that play a central role in pathogenesis of this disease.