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Pathogenesis, clinical features, and diagnosis of endometriosis
Author Robert S Schenken, MD Section Editor Robert L Barbieri, MD Deputy Editor Vanessa A Barss, MD
Last literature review version 19.1: January 2011 | This topic last updated: November 19, 2010 (More) INTRODUCTION — Endometriosis is defined as the presenceof endometrial glands and stroma at extrauterine sites. These ectopic endometrial implants are usually located in the pelvis, but can occur nearly anywhere in the body. Endometriosis is a common, benign, chronic, estrogen-dependent disorder. It can be associated with many distressing and debilitating symptoms, such as pelvic pain, severe dysmenorrhea, dyspareunia and infertility, or it may beasymptomatic, and incidentally discovered at laparoscopy or exploratory surgery. Despite numerous studies, considerable controversy remains regarding the incidence, pathogenesis, natural history, and optimal treatment of this disorder. The epidemiology, pathogenesis, clinical features, and diagnosis of endometriosis will be reviewed here. Treatment is discussed separately. (See "Overview of thetreatment of endometriosis".) PREVALENCE, EPIDEMIOLOGY, AND RISK FACTORS — The prevalence of endometriosis in specific categories of patients has been reported, but the prevalence in the general population is not known. Prevalence is difficult to determine because symptoms are diverse and nonspecific, and because some women are asymptomatic. Estimates of prevalence based upon visualization of the pelvicorgans include the following [1-3]: 1 percent of women undergoing major surgery for any gynecologic indication 1 to 7 percent of women undergoing tubal sterilization 12 to 32 percent of women of reproductive age undergoing laparoscopy to determine the cause of pelvic pain
12 to 32 percent of women of reproductive age undergoing laparoscopy to determine the cause of pelvic pain 9 to 50 percentof women undergoing laparoscopy for infertility versus 6.7 percent of women undergoing laparoscopy with no past infertility. 50 percent of teenagers undergoing laparoscopy for evaluation of chronic pelvic pain or dysmenorrhea (see 'Adolescents' below). Multiple births, extended intervals of lactation, and late menarche (after age 14)  decrease the risk of being diagnosed with endometriosis,whereas nulliparity, early menarche/late menopause, short menstrual cycles, prolonged menses, and müllerian anomalies increase the risk . Endometriosis also appears to be associated with a taller, thinner body habitus and lower body mass index . The prevalence appears to be lower in blacks and Asians than in Caucasians . Growth and maintenance of endometriotic implants are dependent upon thepresence of ovarian steroids. As a result, endometriosis occurs during the active reproductive period: women aged 25 to 35 years [6,7]. It is uncommon in pre- or post-menarchal girls [8-10], and is rare in postmenopausal women who are not taking hormones. PATHOGENESIS — The pathogenesis of endometriosis has not been definitively established. The predominant hypotheses are [11,12]: Theimplantation theory proposes that endometrial cells shed into the uterus during menstruation are transported through the fallopian tubes (‘retrograde menstruation’), thereby gaining access to and implanting on pelvic structures. Similarly, endometriosis that develops in surgical scars (episiotomy, laparotomy) is thought to implant when endometrial cells are transplanted to these locations as a result ofsurgery or delivery. Endometriosis at locations outside the pelvis is explained by dissemination of endometrial cells or tissue through lymphatics and blood vessels. The coelomic metaplasia theory proposes that the coelomic (peritoneal) cavity contains undifferentiated cells or cells capable of dedifferentiating into endometrial tissue. This theory is based upon embryologic studies demonstrating...