Endometriosis, staging, infertility and assisted reproductive technology: time for a rethink.

How endometriosis causes infertility, with the exception of tubal dysfunction caused by adhesions, is unclear. The inflammatory milieu in the pelvis and impaired receptivity of the eutopic endometrium are considered to be possible factors. Anatomical staging systems fail to predict the fertility status of endometriosis patients. Data from assisted reproductive technology cycles consistently suggest that oocytes from patients with endometriosis have a normal potential to develop into euploid blastocysts. Moreover, oocyte or embryo recipients with endometriosis seem to have similar or slightly lower pregnancy and live birth rates compared with recipients without endometriosis, suggesting that eutopic endometrium is not or is only minimally affected, which may be caused by undiagnosed adenomyosis. In-vivo observations from women with endometriomas provide evidence against a detrimental effect of endometriomas on oocytes. Combined with the absence of an obvious improvement in fertility following the surgical destruction or excision of peritoneal endometriosis or from temporary medical suppression of the disease and the associated inflammation, the available evidence makes endometriosis-associated infertility questionable in the absence of tubal dysfunction caused by adhesions. It is likely that no anatomical staging will correlate with fertility beyond assessing tubal function. In patients with endometriosis assisted reproductive technology is as effective as for other indications.