MYTH: Endometriosis is easily diagnosed because it causes distinctive monthly pelvic pain.

FACT: Although severe menstrual pain, pain during intercourse, and low back pain that worsens during menstruation are common symptoms of endometriosis, they can also be caused by other conditions, such as pelvic infections and ovarian cysts. Also, about 30% of patients with endometriosis have no pain.

MYTH: Endometriosis occurs exclusively in women of reproductive age.

FACT: Although mostly affecting younger women, endometriosis also can occur in postmenopausal women on estrogen replacement therapy. Very rarely, endometriosis has also developed in men treated with large doses of estrogen for prostate cancer.

MYTH: Endometriosis can be confirmed by palpating the uterus.

FACT: Although palpation may reveal large or tender endometrial lesions or masses on the uterosacral ligaments, these aren't definitive findings. Imaging studies (such as a transvaginal ultrasound) or diagnostic procedures (such as laparoscopy) should be performed to confirm endometriosis.

MYTH: Endometriosis is a distinct disorder that's rarely associated with other conditions.

FACT: Endometriosis is often associated with one or more concurrent diseases, such as fibromyalgia, chronic fatigue syndrome, systemic lupus erythematosus, Sjogren's syndrome, rheumatoid arthritis, multiple sclerosis, diabetes, hypothyroidism, hyperthyroidism, and Hashimoto's thyroiditis.

MYTH: Development of endometriosis has no hereditary component.

FACT: A familial association exists: Women who have a mother or sister with endometriosis are at much higher risk for developing endometriosis themselves.

Kimberly Dyer is a staff nurse at Tucson Medical Center and a field staff nurse with InteliStaf Healthcare, both in Tucson, Ariz. Selected references for this article are available on request.