Facts about endometriosis

These FACTS are produced by the World Endometriosis Society and the World Endometriosis Research Foundation and have been re-produced with permission.

These facts are current as of the date at the bottom of this page.

This section is particularly aimed at journalists, medical writers, bloggers, etc, who wish to make sure their facts about endometriosis are correct before they publish information about the condition*.

Endometriosis lesions*

Endometriosisis a condition in which tissue similar to the lining inside the uterus (called “the endometrium”), is found outside the uterus, where it induces a chronic inflammatory reaction that may result in scar tissue. It is primarily found on the pelvic peritoneum, on the ovaries, in the recto-vaginal septum, on the bladder, and bowel.

In very rare cases it has been found on the diaphragm and in the lungs [1-2].

Endometriosis affects an estimated 1 in 10 women during their reproductive years (ie. usually between the ages of 15 to 49), which is approximately 176 million women in the world [3-4].

However, endometriosis can start as early as a girl’s first period, and menopause may not resolve the symptoms of endometriosis – especially if the woman has scar tissue or adhesions from the disease and/or surgery.

The symptoms of endometriosis include painful periods, painful ovulation, pain during or after sexual intercourse, heavy bleeding, chronic pelvic pain, fatigue, and infertility, and can impact on general physical, mental, and social well being [1,5].

A general lack of awareness by both women and health care providers, due to a “normalisation” of symptoms, results in a significant delay from when a woman first experiences symptoms until she eventually is diagnosed and treated [5].

There is no known cure and, although endometriosis can be treated effectively with drugs, most treatments are not suitable for long-term use due to side-effects [1,3]. Surgery can be effective to remove endometriosis lesions and scar tissue, but success rates are dependent on the extent of disease and the surgeon’s skills.

Pregnancy may relieve symptoms but is not a cure for the disease. Hysterectomy, with surgical removal of all the disease at the same time, may relieve symptoms, but may not be a “definitive cure” either. Removal of the ovaries at the same time as a hysterectomy is performed increases the chances of pain relief but also results in an immediate menopause.

There is no known cause of endometriosis but it is highly likely that certain genes predispose women to develop the disease [6]. Thus, women have a higher risk of developing endometriosis if their mother and/or sister(s) are also affected [7]. It is possible that age when the menstrual period starts, other gynaecologic factors, and environmental exposures influence whether a woman is affected. Whereas evidence has been weak with regards to exposure to dioxin (an environmental pollutant) [8] some evidence now supports exacerbation of its symptoms due to PCBs.

Some studies have linked the presence of endometriosis with the development of ovarian cancer; however, the association is not definitive and the absolute risk for a given woman with endometriosis is exceedingly low. Whereas endometriosis cells have been localised adjacent to ovarian cancer cells, the former has not been proven to be a pre-cursor to cancer [9-10].

Even though endometriosis is associated with inflammation and immunological dysfunctions, it has not been proven itself to be an autoimmune disease [8].

Resources

There are national support organisations in many countries now. See: https://endometriosis.org/support/

The World Endometriosis Society (WES) convenes the World Congresses on Endometriosis (WCE). The 16th WCE takes place in Sydney, Australia, from 21 to 24 May 2025.

The World Endometriosis Research Foundation (WERF) is the global charity that fosters research in endometriosis with an aim to improve knowledge and treatments through international multi-centre research according to standardised protocols.