Pain is the most common symptom of endometriosis, affecting up to 80 %.

Pelvic pain associated with endometriosis presents as dysmenorrhea, dyspareunia, or chronic noncyclic pelvic pain.

Total lesion volume does appear to correlate directly to the degree of pain.

Pain is typically most intense just prior to menstruation and lasts for the duration of menstruation.

Dysmenorrhea occurs in most women with endometriosis.

Dyspareunia, deep pelvic pain with vaginal penetration, is usually a symptom of advanced endometriosis. Dyspareunia is most pronounced just prior to menstruation.

Adhesions, very common in endometriosis, may also be associated with pain. Adherence of the colon and small bowel along with retroflexion of the uterus from extensive posterior adhesions may occur. Such retroflexion and fixation of the rectosigmoid can result in pressure on the sacrum with consequent back and rectal pain.

Macrophages are responsible for the removal of foreign material such as the endometrial implants. They are present around the endometrial implants and are potent producers of inflammatory mediators such as the prostaglandins.

In women with known endometriosis, the infertility rate is 30–50 %.

Pelvic endometriosis and the resulting inflammatory response can produce dense, fibrotic adhesions that may significantly interfere with both the oocyte release from the ovary and the ability of the fallopian tube to pick up and transmit the oocyte to the uterus.

Endometriosis was the etiology in 14 % of patients undergoing tubal reconstruction for occlusion.

In moderate or severe endometriosis, the pregnancy rates following surgery are 50 and 40 %, respectively, compared with only 7 % when expectant management is practiced.

Intestinal complaints are found in most women with moderate-to-severe disease.

Bowel involvement occurs in 12–37 % of cases of endometriosis.

Rectosigmoid is involved in over 70 %, followed by the small bowel and appendix.

Rectosigmoid disease often results in alterations in bowel habits such as constipation, diarrhea, a decreased caliber of the stool, tenesmus, or, rarely, rectal bleeding. Such symptoms appear more often around the time of menses.

Colonic endometriosis can present with obstruction and may be difficult to differentiate from other causes of large bowel obstruction.

Intestinal resection in asymptomatic patients is probably unwarranted.

Acute or chronic small bowel obstruction develops from extensive fibrotic adhesions.

The next most frequent site of intestinal endometriosis is the appendix.

Endometriosis of the appendix may produce a chronic obstruction of the intestinal lumen with formation of a mucocele or periappendiceal inflammatory mass that is difficult to distinguish from a neoplasm.