All stages of endometriosis are strongly associated with sub-fertility. However, it is not clear how endometriosis reduces fertility rates. Some of the current theories are discussed in detail in this tutorial.
Endometriotic implants in the pelvis and abdomen can most often only be detected through direct visualization (at the time of surgery, either laparoscopy or laparotomy).
Endometriosis can also cause a wide variety of symptoms. Classically, endometriosis is associated with pain during menses. However, many women with severe endometriosis do not seem to have any significant discomfort with their menstrual flows, suggesting that these women have very few sensory nerve fibers along the pelvic peritoneum (where endometriosis most often develops). Endometriosis can form implants along the bladder, bowel or other abdominal organs to produce bladder, bowel or other symptoms.