Endometriosis and IVF treatment outcomes: unpacking the process

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.

Clinical Management of Infertility Associated with Endometriosis

OBJECTIVE

This study aimed to review recent data that affected the clinical management of infertility associated with endometriosis.

DATA SOURCES

We completed a PubMed review of all articles that included the following keywords: endometriosis, infertility, IVF, and ART.

STUDY SELECTION

A study was selected based on the pertinence of the topic addressed in relation to the study's set objectives.

DATA EXTRACTION AND SYNTHESIS

All identified articles were first assessed based on a review of the abstract. Pertinent articles were reviewed in depth.

CONCLUSION

Endometriosis interferes with natural conception primarily by altering the quality of gametes-oocytes and sperm-and early-stage embryos. On the contrary, recent data indicate that gametes and early-stage embryos are not altered in the case of ART. Surgery-a classical approach in yesteryears-does appear to improve ART outcomes and may affect ovarian reserve and the number of oocytes retrieved in ART. Surgery is thus more rarely opted for today and only when necessary; proceeding to fertility preservation prior to surgery is recommended. When ART is performed in women with endometriosis, it is recommended to use an antagonist or progesterone-primed ovarian stimulation approach followed by deferred embryo transfer. In this case, GnRH (gonadotropin releasing hormone) agonist is preferred for triggering ovulation, as it limits the risk of cyst formation as well as ovarian hyperstimulation syndrome. Frozen embryo transfers are best performed in E2 (estradiol) and progesterone replacement cycle.

Impact of endometriosis on the ovarian follicles

A significant body of evidence has supported a negative impact of endometriosis on ovarian follicles; however, the origin and relevance of this ovarian impairment in endometriosis is still a matter of debate. The ovarian damage can be caused by endometriosis itself or by surgeries aiming to remove endometriotic lesions. In this review, we summarized the existing knowledge on the mechanisms by which endometriosis can impact the ovarian follicles, from molecular to clinical points of view. From a molecular standpoint, the presence of endometriosis or its consequences can induce oxidative stress, inflammation, aberrant mitochondrial energy metabolism and inappropriate steroid production in granulosa cells, phenomena that may impair the quality of oocytes to variable degrees. These alterations may have clinical relevance on the accelerated exhaustion of the ovarian reserve, on the ovarian response to gonadotrophin stimulation in IVF cycles and on the competence of the oocytes. Critical points to be considered in current clinical practices related to fertility issues in endometriosis are discussed.

Epidemiology of infertility in women with endometriosis

Endometriosis is a benign, chronic, inflammatory condition affecting up to 10 % of women and characterised by the presence of glands and stroma tissue outside the uterus. Epidemiological and clinical studies demonstrate a consistent association between endometriosis and infertility. However, this relationship is far to be clearly understood and several mechanisms are involved. Available data show that patients with endometriosis have an increased estimated risk of infertility between two and four times compared with the general population. On the other hand, the probability of patients with infertility to have endometriosis is reported up to about 50 % of the cases. Future studies should aim to better elucidate the mechanisms behind endometriosis-associated infertility in order to offer the more appropriate and tailored management for the patients.