Endometriosis is a common health problem among women of reproductive age. Up to one half of pre-menopausal women will have the condition, in which endometrial-like glands and stroma grow in an extrauterine site. The Committee on Practice Bulletins—Gynecology of the American College of Obstetricians and Gynecologists (ACOG) has updated its guidelines on the treatment of endometriosis. Practice Bulletin no. 11 appears in the December 1999 issue of Obstetrics and Gynecology. These guidelines replace Technical Bulletin No. 184, which was published in September 1993.

Etiology

A complete understanding of endometriosis has defied researchers, but there are various theories regarding its etiology, according to ACOG. Menstrual flow that produces a greater volume of retrograde menstruation may increase the risk of developing the disease. Early menarche, regular cycles (especially with an absence of amenorrhea caused by pregnancy), and a longer and heavier flow are also associated factors. Endometriosis is an estrogen-dependent disease; therefore, factors that reduce estrogen levels (e.g., menstrual disorders, decreased body-fat content and smoking) are associated with a reduced risk for developing the condition.

Manifestations

ACOG emphasizes that the clinical manifestations of endometriosis vary and may be unpredictable in presentation and course. Well-recognized manifestations include dysmenorrhea, chronic pelvic pain, dyspareunia, uterosacral ligament nodularity and adnexal mass. However, endometriosis is asymptomatic in many women.

Much debate has centered on the link between endometriosis and infertility. Endometriosis may induce infertility as a result of anatomic distortion caused by invasive growth and adhesions. However, with minimal and mild endometriosis, a cause-and-effect relationship has not been proved, and controlled trials suggest it may not directly cause infertility.

Pelvic pain caused by endometriosis falls into three categories: secondary dysmenorrhea, with pain commencing before the onset of the menstrual cycle; deep dyspareunia that is exaggerated during menses; or sacral backache with menses.

The pain associated with endometriosis has little relationship to the type of lesions seen by laparoscopy. However, it has been shown that the depth of endometriosis lesions correlate with severity of pain. It is thought that painful lesions are those that involve peritoneal surfaces innervated by peripheral spinal nerves, not those innervated by the autonomic nervous system.

Diagnosis

The ACOG committee states that a histologic examination should be done to confirm the presence of endometrial lesions, especially those with a nonclassical appearance. Only an experienced surgeon familiar with the protean appearances of endometriosis should rely on visual inspection to make the diagnosis. Peritoneal biopsy may be used to diagnose questionable peritoneal lesions.

A noninvasive alternative to tissue biopsy is being sought by researchers. Correlating moderate and severe endometriosis and CA 125 concentration in serum is one possibility. However, the utility of measuring serum CA 125 levels as a diagnostic marker is limited, especially in women with mild or minimal disease. Peritoneal fluid levels appear to be better for detecting minimal to moderate disease.

Recommendations

According to the ACOG committee, current evidence suggests that pain caused by endometriosis can be managed medically. Progestins, danazol, oral contraceptives, nonsteroidal anti-inflammatory drugs and gonadotropin-releasing hormone (GnRH) agonists have all been shown to reduce the size of lesions. However, no medical therapy has been proved to eradicate the lesions. Furthermore, there is no evidence that such treatment affects the future fertility of women with endometriosis. Studies are lacking that suggest the absence of treatment is associated with a decline in fertility.

Surgery for women with endometrial pain is associated with significant reduction in pain during the first six months following surgery. However, up to 44 percent of women experience a recurrence of symptoms within one year. Data about whether surgical therapy influences long-term therapy are lacking, and there are no data to indicate whether medical or surgical therapy results in better fertility outcomes.

The following recommendations from ACOG are based on Level A (good and consistent) scientific evidence:

• For pain relief, treatment with a GnRH agonist for at least three months or with danazol for at least six months appears to be equally effective in most women.

• When relief of pain from treatment with a GnRH agonist supports continued therapy, the addition of add-back therapy reduces or eliminates GnRH-induced bone mineral loss without reducing the efficacy of pain relief.

The following recommendations from ACOG are based on Level B (limited or inconsistent) scientific evidence:

• Therapy with a GnRH agonist is an appropriate approach to the management of the woman with chronic pelvic pain, even in the absence of surgical confirmation of endometriosis, provided that a detailed initial evaluation fails to demonstrate some other cause of pelvic pain.

• For pain relief, oral contraceptives and oral or depot medroxyprogesterone acetate are effective in comparison with placebo and may be equivalent to other more costly regimens.

• Hormone replacement therapy with estrogen is not contraindicated following hysterectomy and bilateral salpingo-oophorectomy for endometriosis.

The following ACOG recommendations are based primarily on Level C data (consensus and expert opinion):

• For severe endometriosis, medical treatment alone may not be sufficient.

• Because endometriosis often is unpredictable and may regress, expectant management may be appropriate in asymptomatic patients.