Most women who have endometriosis, in fact, do not have symptoms. Of those who do experience symptoms, the common symptoms are pain (usually pelvic) and infertility. Pelvic pain usually occurs during or just before menstruation and lessens after menstruation. Some women experience pain or cramping with intercourse, bowel movements and/or urination. Even pelvic examination by a doctor can be painful. The pain intensity can change from month to month, and vary greatly among women. Some women experience progressive worsening of symptoms, while others can have resolution of pain without treatment.

Pelvic pain in women with endometriosis depends partly on where the implants of endometriosis are located. Deeper implants and implants in areas with many pain-sensing nerves may be more likely to produce pain. The implants may produce substances that circulate in the bloodstream and cause pain. Lastly, pain can result when endometriosis implants form scars. There is no relationship between severity of pain and how widespread the endometriosis is (the "stage" of endometriosis).

Endometriosis can be one of the reasons for infertility in otherwise healthy couples. When laparoscopic examinations are performed for infertility evaluations, endometrial implants can be found in some of these patients, many of whom may not have painful symptoms of endometriosis. The reasons for a decrease in fertility are not completely understood, but might be due to both anatomic and hormonal factors. The presence of endometriosis may involve masses of tissue or scarring (adhesions) within the pelvis that may distort normal anatomical structures, such as Fallopian tubes, which transport the eggs from the ovaries. Alternatively, endometriosis may affect fertility through the production of hormones and other substances that have a negative effect on ovulation, fertilization of the egg, and/or implantation of the embryo.

Other symptoms related to endometriosis include lower abdominal pain, diarrhea and/or constipation, low back pain, irregular or heavy menstrual bleeding, or even blood in the urine. Rare symptoms of endometriosis include chest pain or coughing blood due to endometriosis in the lungs, headache and/or seizures due to endometriosis in the brain.

Source: Medicinenet.com