a gynecological disorder characterized by the tumorlike growth in various organs of endometrioid tissue that structurally and functionally resembles the uterine mucous membrane, or endometrium. The disease generally develops in women between the ages of 30 and 50. Its cause has not been established. One theory is that the condition is caused by the migration of endometrial tissue through blood vessels and the uterine tubes to pelvic organs and other parts of the body. A distinction is made between endometriosis interna (endometrial growths in internal genital organs—most often the uterus and ovaries) and endometriosis externa (growths outside the uterus—in the umbilicus, perineum, intestine, and elsewhere).
Endometriosis is characterized by cyclical changes in the endometrioid masses and by hemorrhages in focuses of the growths during menstruation. Pain is felt before and during menstruation. Endometriosis of the uterus, also known as adenomyosis, intensifies and prolongs menstrual bleeding. The condition may result in sterility. Endometriosis is usually treated by hormonal preparations and uterine agents; some cases require surgery or radiotherapy.