What is endometriosis?

Endometriosis is a complex disease that can recur in certain cases and generate chronic pain. Endometriosis, a disease that has long been ignored and is sometimes very difficult to live with on a daily basis, is defined as the presence outside the uterine cavity of tissues similar to the uterine mucous membrane, which is affected by hormonal changes during each menstrual cycle.

Extract from the introduction by Professor Charles Chapron in Misconceptions about endometriosis -February 2020 – Cavalier bleu editions.

Endometriosis and the menstrual cycle: the concept of « Endometriosis Life»

The concept of “Endometriosis life”: this is an innovative concept which takes a comprehensive approach to the menstrual cycle, infertility and endometriosis.

Endometriosis has the potential to affect all women of childbearing age: it is a condition of the endometrium and the menstrual cycle and should be monitored from puberty to the menopause. It is impossible to understand and treat endometriosis and/or infertility without taking into account the menstrual cycle.

Although the physiopathology of endometriosis is far from clear-cut and involves numerous hypotheses (metaplasia, induction, metastasis, immunological, genetic, epigenetic and environmental, stem cells, etc.), it is impossible to understand this disease without taking into account the regurgitation theory known as the “implantation theory”.

During menstruation, under the effect of uterine contractions, some of the blood is discharged through the fallopian tubes into the abdominopelvic cavity. This theory would explain the majority of cases of endometriosis.

This blood contains endometrial cells, fragments of uterine mucous membrane, which, instead of being destroyed by the immune system, will be implanted and then, as a result of subsequent hormonal stimulation, grow on the surrounding organs (peritoneum, ovary, fallopian tube, intestine, bladder, ureter, diaphragm, etc.).

Extract from the introduction by Professor Charles Chapron in Misconceptions about endometriosis -February 2020 – Cavalier bleu editions.


In fact, endometriosis is a condition linked to the menstrual cycle that is:

  • Hormone-dependent: Painful symptoms are linked to the menstrual cycle, which explains the effectiveness of hormonal treatment that, by blocking ovulation and menstruation, offers patients relief.
  • Neurological: Endometriosis cells have the ability to penetrate nerves and so contribute to the pain experienced by patients.

There isn’t one, but many endometrioses

Endometriosis develops differently from one woman to the next.

It is defined as a heterogeneous condition: Pain in endometriosis patients can present itself in a wide variety of forms: dysmenorrhoea, dyspareunia, chronic pelvic pain, digestive and/or urinary disorders with perimenstrual recrudescence, etc.

Patients can also experience these same symptoms without having endometriosis. The difficulty is therefore to ensure that the pain is related to endometriosis and not another condition.

To find out more: LUNA explains: the symptoms of endometriosis

While there is little certainty about endometriosis, it can be defined in the following way, according to 3 types (or phenotypes):

  • Superficial endometriosis, when the implants remain superficial on the surface of the peritoneum (tissue that lines the entire abdominopelvic cavity) and/or ovaries
  • Ovarian endometriosis or endometriotic cysts (endometriomas), when after successive heavy bleeding every month the lesions create a cyst in the ovary
  • Deep endometriosis when the lesions penetrate the abdominopelvic organs (bladder, ureter, intestine, vagina, …).

Endometriosis is also said to be multifocal, in other words the lesions are rarely isolated: these three types of endometrioses can also be associated in the same patient and do not cause the same symptoms.

It is also necessary to specify that there is no link between the intensity of the pain and the type of endometriosis: a patient suffering from deep endometriosis may present less painful symptoms than a woman affected by so-called superficial endometriosis.

The diagnosis of endometriosis

Whatever the health system, in whichever country worldwide, the delay between the first appearance of symptoms and the diagnosis of endometriosis is excessively long, between 6 and 10 years.This situation must change for all women who suffer from this chronic disease which has an impact on daily life and quality of life.

Patients should be offered:

  • Firstly, a comprehensive interview (see paragraph above), to help identify patients at risk of endometriosis
  • Secondly, a gynaecological examination carried out by a practitioner familiar with the condition
  • Thirdly, an imaging assessment carried out by a specialist in endometriosis.

Recent years have seen considerable progress in gynaecological radiology (vaginal ultrasound, nuclear magnetic resonance imaging: MRI). It is now possible to diagnose ovarian cysts or endometriomas and deep lesions without the need for laparoscopy, which is a surgical procedure under general anaesthetic.

The most common radiological examination is a vaginal ultrasound. An MRI is only taken as a second option, either in the context of deep endometriosis to determine the exact location of the nodules, or to quantify the importance of associated adenomyosis (see glossary) and very often if surgery is being considered.

Endometriosis and fertility

Infertility is defined as the difficulty a couple have conceiving a child after 12 to 24 months of regular, unprotected sexual intercourse. Whether it’s a question of male or female infertility, the couple must see a fertility specialist. This is the case for about one in seven couples in France. In the absence of any underlying medical condition, the probability of a couple conceiving naturally is 20 to 25% per menstrual cycle.

In some women, endometriosis may be painless but it may have an impact on fertility. It can therefore be diagnosed during an infertility assessment. In fact, endometriosis is the main cause of infertility.

However, the connection between endometriosis and infertility is not automatic: 40% of women with endometriosis experience fertility problems. The presence of tissue, such as ovarian cysts, can create physiological obstacles to fertilisation in the case of major lesions.

In short, women with infertility problems very often have endometriosis problems, but endometriotic women are in most cases not infertile.

The impact of endometriosis and late diagnosis on patients

It still takes a very long time to diagnose endometriosis: from an average of 7 years to as long as 10 years! This has major consequences for patients.

The later the diagnosis, the greater the difficulties experienced by patients, whether at school, at home, at work, etc., and the greater the risk of the disease progressing and developing clinical complications.

Women who remain undiagnosed often find themselves in a state of limbo that generates anxiety and anguish for them and their families, and delays the implementation of appropriate care protocols.

On a psychological level, this lack of diagnosis deprives women of the social recognition they deserve and may lead to them feeling misunderstood and dejected for years, often in silence.

Diagnosis is a public health issue

For patients

The diagnosis of endometriosis is essential to:

  • offer structured and adapted care
  • minimise the development of the condition and its consequences

For health professionals

Identifying the disease is key to providing care and adapting support for patients. This delay is responsible for a waste of medical resources and additional costs for the entire medical system.

For society

Endometriosis has a major economic cost in terms of lost productivity, absenteeism and all the indirect effects of physical and psychological impact on endometriosis patients.

Economic cost

13billion €

in France

80billion $

in the USA

There is a lack of gynaecological care: today there are too few gynaecologists and endometriosis specialists compared to the number of women who need support.

4000 gynaecologists for 14M women in France Or 3500 women / gynaecologist (bloc)

Endometriosis figures

Endometriosis affects 1 woman in 10

5 specialist consultations before diagnosis

Time to diagnosis: From 6 to 12 years

40 % of patients encounter fertility problems