Endometriosis is the presence of endometrial glandsE and stroma in any extrauterine site, and may be sus-pected based on history, symptoms, and physical examination as well as laboratory and imaging informa-tion. Like the endometrial tissue from which it is derived, endometriosis implants and cysts respond to the hormonal fluctuations of the menstrual cycle. Laparotomy or laparos-copy may reveal lesions consistent with endometriosis, but because lesions may be small or atypical or caused by pathology other than endometriosis, only proven tissue biopsydiagnosis is diagnostic. Many women with endometriosis areasymptomatic, and diagnosis is confirmed only when sur-gery is performed for other indications.
It is estimated that 7% to 10% of women in the gen-eral population have endometriosis. Pelvic endometriosis is present in 6% to 43% of women undergoing steriliza-tion, 12% to 32% of women undergoing laparoscopy for pelvic pain, and 21% to 48% of women undergoing laparoscopy for infertility. Endometriosis usually occurs in women of reproductive age, and is less frequently found in postmenopausal women. Endometriosis occurs more often in women who have never had children.
Some evidence suggests that endometriosis may have a genetic component. Women with first-degree relatives with endometriosis have nearly a 10-fold increased risk of developing endometriosis. The proposed mechanism of inheritance is polygenic and multifactorial.