Key points for diagnosis:
(1) Secondary dysmenorrhea is often found and about 40% accompanied with primary or secondary sterility among woman of childbearing age.

(2) Abdominal pain, which appears 1-2 days before menstruation, becomes most serious on the first day of menstruation and gradually gets relieved after menstruation. The location of pain is usually in the lower abdomen and lumbosacral region, radiating to vagina, perineum, anus or medial side of leg. Focus in the retrouterine excavation and uterosacral ligament may lead to coital pain, distending and prolapsing sensation in anus that are worsened during menstruation. It may be accompanied by prolonged menstrual duration and increased menorrhea. Rupture of cyst in endometriosis may result in acute abdominal pain and intra-abdominal bleeding.

(3) The basal body temperature usually appears in bidirectional curve. Gynecological examination finds fixed retroversion of uterus. Painful hard nodules can be felt on the postuterine wall and uterosacral ligament. Fixed and painful cystic mass can be felt beside the uterus. Occasionally purplish nodules can be found in vaginal fornix and cervix.

(4) Type B ultrasonic examination suggests thick liquid in unilateral or bilateral ovary or enlargement of the uterus.

(5) Peritoneoscopy may find endometriosis focus or bluish-purplish or brownish sticky cystic enlargement of ovary in the retrouterine excavation and sacral ligament. Biopsy of doubtful focus is necessary for accurate diagnosis.

(6) Endometriosis should be differentiated from primary dysmenorrhea, hysteromyoma, benign and malignant uterine tumor, chronic pelvitis, and pelvic tuberculosis, etc.