Endometriosis is defined as the presence of ectopic endometrial tissue which induces a local inflammatory reaction. Usually, this tissue is located at any level in the pelvic region, but extrapelvic locations have been described. It is a chronic disease whose cause is unknown, although a genetic predisposition has been proven. It is estimated that endometriosis affects 7-15% of women of fertile age, and up to 30-40% of women with endometriosis have infertility.
Assisted reproduction techniques (ART) are the treatment of many causes of infertility, including endometriosis. The results of assisted reproduction in women with endometriosis appear to be somewhat worse than those obtained from women without endometriosis. Some authors have proven a significant reduction in implantation and pregnancy rates in these patients.
The worst pregnancy rate and implantation is believed to be originated in a poor oocyte quality, which can lead to a lower rate of fertilization. This poor oocyte quality produce poorer quality embryos with a reduced capacity to implant, particularly in severe endometriosis.
On the other hand, endometrial receptivity does not appear to contribute to the reduction of results of ART in these women.
In an attempt to improve ART outcomes in women with endometriosis, different strategies have been proposed prior to the cycle realization, with different results.
Surgical resection of endometriomas (endometriosis cysts) before the cycle of IVF/ICSI may adversely affect the results. On the other hand, careful laparoscopic cystectomy appears not to affect the ovarian response to stimulation.
In addition to surgical approaches, have been tried different medical treatments to improve the results of IVF / ICSI in women with endometriosis. It has been suggested that treatment with Danazol prior to IVF may improve results. Similarly, prolonged treatment with GnRH analogues few months before IVF could improve the implantation and pregnancy rates. Unfortunately, many of these studies were not randomized and / or controlled so that the true value of therapy with GnRH analogues before IVF in women with endometriosis still needs to be valued. A recent meta-analysis showed that a 3-6 month treatment with GnRH analogues before IVF increased 4 times the odds of clinical pregnancy in women with endometriosis. Nevertheless, these results were concluded from 165 patients and 78 pregnancies, included in 3 clinical trials, which was not specifically to patients with endometriomas.
The lack of studies with proper design, suggests that there is insufficient evidence at present to establish firm recommendations in this regard. This study will contribute to increasing scientific evidence to recommend or not pretreatment with GnRH agonists before IVF en patients with endometriosis.