Endometriosis is a condition that is characterized by the presence of endometrial tissue in unusual locations. Normally, endometrial tissue lines the uterine cavity, where it thickens during each menstrual cycle in preparation for the arrival of a fertilized ovum. If fertilization does not occur, the endometrium is shed (menstruation).
With endometriosis, abnormal deposits of endometrial tissue are found outside the uterus: in or on the ovaries, in the peritoneal cavity of the pelvis, along the ligaments that suspend the uterus, or in the pouches and recesses that surround the pelvic organs.
At least three theories have been suggested to explain the cause of endometriosis. The most popular notion proposes that endometrial tissue is refluxed through the fallopian tubes during menstruation; these fragments of tissue then develop their own blood supply wherever they come to rest.
Two other hypotheses involve the transformation of certain native tissues—such as the covering of the ovaries—or the differentiation of “embryonic rests” (remnants of tissue left behind during embryonic development) into endometrial tissue.
Whatever the underlying cause, endometriosis typically becomes troublesome during the reproductive years when these ectopic tissues respond to ovarian hormones. Symptoms are usually worse just prior to—and subside shortly after—monthly menstruation.
Endometriosis affects up to 45% of women of reproductive age. Between 1990 and 1998, endometriosis was the third most common gynecologic diagnosis listed in hospital discharge summaries for women 15 to 44 years of age. (Velebil P, et al. Rate of hospitalization for gynecologic disorders among reproductive-age women in the United States. Obstet Gynecol 1995;86:764-9)
Signs and Symptoms of Endometriosis
- Pelvic pain (the most common complaint)
- Back pain
- Hip or groin pain
- Painful intercourse
- Painful periods
- Pain with bowel movements
- Pain with urination
- Infertility (approximately 20% of women undergoing infertility evaluation are found to have endometriosis, although this may not necessarily be the cause of their infertility)
Risk Factors for Endometriosis
- First-degree relative (mother or sister) with endometriosis
- Prolonged menstrual flow (more than six days)
- Short menstrual cycle (less than 28 days between periods)
Obesity and smoking actually reduce the risk of endometriosis, possibly due to their influences on hormone production and blood flow, respectively (Cramer DW, Missmer SA. The epidemiology of endometriosis. Ann N Y Acad Sci 2002;955:11-22)
Diagnosis of Endometriosis
While blood tests, MRI, CT or ultrasound may be helpful, there are no sufficiently sensitive signs, symptoms, or tests that enable accurate diagnosis of endometriosis. Most experts agree that direct visualization and biopsy of endometrial lesions (usually via laparoscopy) is the most useful means of diagnosis, but the correlation between visual diagnosis and biopsy-proven endometriosis is relatively poor. (Mounsey A, et al. Diagnosis and management of endometriosis. Am Fam Phys 2006;74(4):594-600)
Thus, it is reasonable to treat endometriosis based on history and physical examination after other potential causes for symptoms are excluded. Patients whose symptoms persist after a course of empiric therapy should be referred to a surgeon for laparoscopy.
Treatment of Endometriosis
Pregnancy and menopause are associated with a resolution of endometriosis symptoms. Therefore, in women who don’t desire fertility, treatments are based on manipulating hormones to decrease endometrial stimulation. In addition to analgesics, oral contraceptives, Provera, danazol, or gonadotropin-releasing-hormone analogs may be prescribed.
For women who wish to maintain fertility, laparoscopic ablation of lesions is the preferred treatment. Controversy surrounds the effectiveness of this approach, however.
Women who exhibit severe or intractable symptoms may undergo ablation of specific pelvic nerves or even total hysterectomy.
Endometriosis remains a problematic condition that requires individualized evaluation and treatment.
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