Overview of Endometriosis

Endometriosis is the abnormal growth of endometrial cells outside the uterus. The growths are commonly referred to as "endometrial implants." Endometriosis affects 10 to 15 percent of women and is a chronic, sometimes painful condition that can lead to infertility. Causes of endometriosis are unknown.

Diagnosis of endometriosis usually involves a laparoscopy, a complete medical history, a physical examination, and other tests. Treatment typically involves medication and/or surgery.

Endometrial implants typically inset in other parts of the reproductive tract, including the ovaries, fallopian tubes, the inside lining of the abdominal cavity, and the outside surfaces of the uterus or intestines. They can also occur in other parts of the body, including the liver, legs, lungs, and rarely, the brain.

The implants are not malignant (cancerous), but the disease may be progressive and symptoms worsen as the patient experiences more menstrual cycles. Because they are made of the same uterine tissue that is shed during menstruation, endometrial implants also break up monthly. The result is internal bleeding, inflammation, chronic pelvic pain, and the formation of blood-filled cysts and scar tissue.

Pain is the most prevalent symptom, and nearly 90 percent of women with chronic pelvic pain have endometriosis. Scar tissue in the fallopian tubes can interrupt an egg's passage, resulting in infertility. Some patients do not know they have endometriosis until they have an infertility evaluation. As many as 50 percent of infertile women have endometriosis. About one-third of women with endometriosis do not experience symptoms.

There are many medical causes of endometriosis. Any woman can experience the pain and/or infertility associated with endometrial implants.

What are endometrial cells?

The endometrium is the mucous surface that lines the inside of the uterus. It contains several layers of cells (i.e., endometrial cells) that vary in appearance and number throughout the menstrual cycle, as the levels of estrogen and progesterone fluctuate.

During the luteal phase (the two-week period just before a woman bleeds), for example, the endometrium is thick, its cells are enlarged, the glands bulge, and the arteries are swollen. At menstruation, the endometrium sheds. Following menstruation, new cells grow and the endometrium regenerates. The cells that make up the endometrium normally grow only inside the uterus.

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 31 Oct 2000

Last Modified: 14 Sep 2015