Theoretically, endometriosis leads to a decline in fertility, and some studies show that it may reduce the success rate in artificial reproductive treatment (ART). The reasons for the decline in the success rate of IVF include pelvic inflammation and changes in the pelvic environment (such as immunocytes and cytokines, etc...), hormonal changes, abnormal fallopian tube function, and changes in endometrial receptivity. However, whether medication (GnRH agonist and antagonist) or surgery will improve pregnancy rates has been controversial for many years. The following are the recommendations of the American Society of Reproductive Medicine (ASRM) and the European Society of Human Reproduction and Embryology (ESHRE) on the treatment of chocolate cysts in 2012 and 2013:

 We can separate two parts to discuss the success rate of ART: egg quality and endometrial environment.

• In terms of egg quality, although much research points out that endometriosis may reduce the quality of eggs; however, according to the data of SART in 2014, in 353,022 cycles of IVF treatment, when endometriosis is the only factor, the number of eggs retrieved, fertilization rate, implantation rate, pregnancy rate, and live birth rate are all not affected. Additionally, whether the use of GnRH antagonist or agonist before starting the treatment will improve the number of eggs retrieved, fertilization rate, and the development of embryos is still controversial. 

• In terms of endometrial receptivity, it shows that patients with endometriosis have higher progesterone resistance. However if the endometrial receptivity array (ERA) is used to detect the gene expression of the endometrium, the severity of the disease has little correlation with the results of ERA.

Interestingly, in a retrospective study of 374 patients who had undergone IVF treatment and failed more than once, 47% in 36 patients with adenomyosis, their implantation window changed, compared with only 21% of the 338 patients in the control group. 

• In conclusion, whether it is necessary to treat with medication or surgery before the IVF treatment, still need to consider each person's situation: including age, disease severity, egg reserve, and if there are other effects (such as pain, malignant possibility, or other factors that may cause infertility). As for medication before embryo transfer, it is still controversial; in addition to endometrial receptivity, reducing chronic inflammation of the pelvis may also be one of the factors considered by physicians.

Note 1: The conclusion is based on a Cochrane literature review in 2006, but the literature review believed that the cited literature may be biased due to poor experimental methods. Therefore, it is believed that the results of the review need more evidence to verify. The Cochrane literature review in 2019 has overturned the conclusion in 2006 and believes that medication before ART has no obvious benefit. However, the 2019 review has the same problem as the 2006 review: the literature may be biased.