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Endometriosis at a glance

  • Endometriosis is when tissue that lines the uterus (endometrium) begins to grow in areas outside the uterus.
  • Women with endometriosis may experience infertility, pain or discomfort that intensifies during menstrual periods or sexual intercourse. Some women may not have any symptoms of endometriosis.
  • The cause of pain is uncertain, but research shows that some women have abnormally high levels of free radicals and chemical messengers, which trigger pain perception.
  • A surgical evaluation offers the only conclusive diagnosis of the condition.

What is endometriosis?

Endometriosis, also called endo, is a condition in which the lining of the inside of the uterus (endometrium) grows outside of the uterus. The most common sites for endometriosis are the ovaries and the peritoneum (the thin lining that covers the organs in the pelvis).

The cause of endo is widely debated but currently unknown.

The two most common symptoms of the condition are pain and/or infertility. However, many women have no symptoms at all.

The chance a woman has endometriosis depends on her family and medical history, as shown in this table:

Chance of having endometriosis

General population


Sister or mom has endometriosis


Infertility with no other cause found


Chronic pelvic pain


Chronic pain and infertility


Like normal endometrium (uterine lining) tissue, endometriosis grows in response to the estrogen produced by the ovaries. In most cases, it stops growing and may regress in the presence of progesterone.

When a woman is pregnant, she produces high levels of progesterone; thus endometriosis often regresses and pain improves during pregnancy.

Similarly, when a woman becomes menopausal, she stops producing estrogen. Endo rarely causes symptoms after menopause.

How does the condition cause pain?

The exact reasons why endometriosis causes pain are still unknown. Researchers have established that some women with endometriosis have abnormally high levels of free radicals and chemical messengers, which trigger pain perception.

Pain may also be caused by the endometrium growing in a confined space, or by anatomy distortion from endometriosis-induced scarring.

How does it cause infertility?

The American Society for Reproductive Medicine reports that 30% to 50% of women with endometriosis may become infertile. The condition causes infertility in a variety of ways. When scar tissue or adhesions develop, the woman’s reproductive anatomy can become distorted.

In some cases, sheets of adhesions can create a barrier between the ovary and the fallopian tubes, blocking the ability of the tubes to capture an egg after ovulation. In other cases, adhesions can cause an ovary or a tube to become stuck in an unnatural location, making it difficult for the egg and the tube to meet.

For reasons not fully understood, endo can also affect the quality of a woman’s eggs. This does not mean a woman is more likely to have a baby with a birth defect. It simply means that she may be less likely to become pregnant.

Diagnosing endo

Patient history, physical examination and studies such as an ultrasound or hysterosalpingogram (HSG) may suggest that a woman has endometriosis. However, the condition is only conclusively diagnosed by surgical evaluation.

Treatment options for pain caused by endometriosis

Like most disorders, the treatment for endometriosis depends on the patient’s goals.

There are three common ways to treat pain caused by endo:

    1. Mimicking pregnancy by taking oral contraceptive pills, and/or oral or injectable progestational agents.
    2. Mimicking menopause through Lupron injections that cause the ovaries to stop producing estrogen – similar to menopause.
    3. Surgery to remove the lesions, or to remove the ovaries and cause actual menopause.

Each of these treatments has its advantages and disadvantages. Selecting the best treatment for you should involve an informative collaboration with your doctor.

Treatment options for infertility from the condition

The extent of endo and the detrimental effect on egg quality is widely variable among patients, so it is difficult to predict what treatments will be required to achieve pregnancy.

Some patients only need oral ovulation induction medicines such as clomiphene citrate. Other women will require artificial inseminationsuperovulation, or in vitro fertilization (IVF). In severe cases, a woman may require egg donation.

Sometimes infertility caused by the condition can be overcome by having surgery. If a woman has mild endometriosis, surgery may be an option; however, fewer than 1 in 10 women actually benefit from surgery.

In rare cases, when the ovary and the fallopian tubes have become separated from each other, getting pregnant naturally can be very challenging. Restoring normal anatomy through surgery may improve these chances, but most of these women will still require more advanced fertility treatments such as IVF.