There is a very good review of the effects of endometriosis on fertility and the rationale for various types of treatment including surgery, injectable medications with IUI and eventually IVF.
Endometriosis creates an inflammatory environment in the pelvis and reproductive system, leading to the development of adhesions (scar tissues) and endometriomas (cysts known as chocolate cysts), which cause chronic pelvic pain symptoms and can compromise fertility.
There is no question that in the advanced endometriosis (Stage III-IV) fertility is compromised. The fecundity rate (chance to conceive) in women under the age of 35, with severe endometriosis, is in the neighborhood of 1% in each menstrual cycle as compared to 15%-25% in the healthy fertile women of the same age. The effect of early (Stage I-II) endometriosis on fertility is less clear and controversial. There is no question that some women with mild to moderate endometriosis can conceive spontaneously or with minor fertility treatment. However, the fecundity rate per cycle in women under 35 with early endometriosis is only in the neighborhood of 2%-3%, again far lower than the 15%-25% fertility rate among their peers.
There is a discussion of how endometriosis affects fertility and the rationale and chances of success of each in the various stages of endometriosis.
At RPMG our newest strategy for women with endometriosis needing IVF is to freeze all the embryos and transfer them after a cycle of birth control pills in a frozen embryo cycle which appears to restore the success rates of those with endometriosis to our general patient population. The theory behind this strategy is that there is some adverse effect from the stimulation and development of the egg(s).
This article is must reading for those struggling to conceive who suffer from endometriosis.