Causes Of Endometriosis

What is Endometriosis?

Endometriosis is a chronic condition whereby the endometrial tissue grows out of the uterus.1 It is estimated that this gynaecological condition affects one in ten women who are of reproductive age worldwide.1 Endometrial tissue can usually be found in the uterine lining, and its role is to prepare for implementation if pregnancy occurs, and if it does not, to trigger menstruation. 2

The causes of this condition can be both genetic and environmental (epigenetic). Within endometriosis, endometrial tissue can start growing in the pelvic compartment and is tissue dependent on the hormone estrogen.3 Diagnostic tools for this condition can include obtaining a histological diagnosis, ultrasounds, and a laparoscopy.3 In a scoring system for endometriosis, there are three stages, and these are: mild, moderate, and severe.Treatment options for the pain can include surgery, drugs that suppress endometrial cell proliferation (GnRH), and oral contraceptives.As a result of this condition, women are highly susceptible to developing infertility due to chronic pelvic inflammation, and in this case, IVF (in vitro fertilisation) is usually suggested, although this differs case by case. 4

Symptoms of endometriosis

According to ‘Endometriosis UK’, symptoms can be categorised into 4 categories: 


  • During periods 5
  • Pelvic pain 5
  • Throughout physical examinations 5
  • After or throughout sexual intercourse 5 

Bowel and Bladder 

  • Painful bowel movements 5
  • Diarrhoea, constipation or bloating during period 5


  • Heavy periods 5
  • Spotting in between periods 5
  • Blood clots during menstrual cycle  5


  • Changes in mental health e.g depression
  • Fatigue  5

The above is just an outline of what potential symptoms can crop up throughout this chronic condition. Symptoms can differ according to the individual, which is why it is important to constantly track them and their pain levels. If you feel that your period pain is too severe, this could be an early warning sign of this condition, and a medical appointment should be made in order to formulate the right treatment plan for you.

What can cause endometriosis?

Endometriosis is a multifaceted condition which means that it does not have one sole cause. Multiple factors can contribute to the development of this condition, notably high-stress levels, retrograde menstruation, hormonal dysregulation, endometrial cell transport, autoimmune issues, and the implementation of a surgical scar. 

Retrograde menstruation

Retrograde menstruation, medically speaking, is when fragments of the endometrium flow back through the fallopian tube into the peritoneal cavity.6 In other words, fragments of the uterine lining are transported back through the fallopian tubes and are deposited into other bodily organs, which can include the colon, stomach, liver, duodenum, and spleen.7 Within endometriosis, the tissue with the endometrial cells/debris is implemented into the pelvic cavity during menstruation.8 However, at present, this cause is theoretical, as 76-90% of women with normal menstruation also develop retrograde menstruation.8 Multiple theories exist suggesting that retrograde menstruation, imperforate hymen and cervical stenosis increase the risk rate of developing endometriosis.8 This is a disputed topic in the realms of medicine as retrograde menstruation can’t be proven as a cause for developing endometriosis amongst prepubertal girls, newborns or males.8 

Hormonal dysregulation

For people who suffer from endometriosis, there is a higher than usual production of the hormone oestrogen and progesterone. As the endometrial tissue starts to develop outside of the uterine cavity, this provokes the signalling  of these two hormones to be disrupted.9 Oestrogen  dominance occurs, and progesterone is resisted. 9 This imbalance between oestrogen and progesterone increases the inflammation rate as well as the symptom of pelvic pain .9 Hormonal dysregulation is one of the main causes for this condition as it is oestrogen dependent.

Endometrial cell transport

Endometrial cells are thought to be transported either via the lymphatic or the circulatory system in the body.10 When travelling in the bloodstream, the cells enter via the capillary vessels in the uterus and travel to other locations and start embedding themselves due to a hormonal response.11 Another mode of travelling is through the lymphatic system, as there are lymph nodes in the uterus, and this can travel to other parts of the body to form endometriotic lesions.11 Endometriotic lesions have a high lymphatic vessel density, therefore, signifying that the cell's  primary mode of transport  is through the lymphatic system.11 

Autoimmune issues

Immune deficiencies, which are issues with the body's immune system, can trigger the body to not be able to recognise the endometrial tissue that is growing outside of the uterus.12 There is also a higher risk of developing endometriosis if you already have one of the following autoimmune diseases, according to a study: arthritis, inflammatory bowel disease, celiac disease and autoimmune thyroid disease.13

Implementation of a surgical scar

Surgical scar endometriosis only occurs in 2% of the population and is, therefore, a very small subset of endometriosis.14 The location of the surgical scar is usually on the fallopian tubes, ovaries, hernia sacs and recto-vaginal septum.14 The scar resulting from a caesarean surgery during pregnancy can also increase the risk of  scar endometrioma and thus, endometriosis.14


In conclusion, this article looked at the potential triggers of the condition of endometriosis. There is not one single trigger, although the main trigger is the hormone imbalance between oestrogen and progesterone. Endometrial cell transport was discussed, which is not a cause but rather an explanation of how it is transported around the body via the lymphatic or the circulatory system. Autoimmune diseases increase the risk of a person developing endometriosis, and so does a surgical scar. 


  1. Symons L, Miller J, Kay V, Marks R, Liblik K, Koti M et al. The Immunopathophysiology of Endometriosis. Trends in Molecular Medicine [Internet]. 2018 [cited 11 October 2022];24(9):748. Available from:
  2. Critchley H, Maybin J, Armstrong G, Williams A. Physiology of the Endometrium and Regulation of Menstruation. Physiological Reviews [Internet]. 2020 [cited 11 October 2022];100(3):1149. Available from:  
  3. Agarwal S, Chapron C, Giudice L, Laufer M, Leyland N, Missmer S et al. Clinical diagnosis of endometriosis: a call to action. American Journal of Obstetrics and Gynecology [Internet]. 2019 [cited 11 October 2022];220(4):357. Available from:
  4. Vercellini P, Viganò P, Somigliana E, Fedele L. Endometriosis: pathogenesis and treatment. Nature Reviews Endocrinology [Internet]. 2013 [cited 11 October 2022];10(5):264-268. Available from:  
  5. Symptoms | Endometriosis UK [Internet]. [cited 11 October 2022]. Available from: 
  6. Harada T. Endometriosis. 1st ed. Tokyo: Springer Japan; 2014. 
  7. Anatomy, Abdomen and Pelvis, Peritoneum. StatPearls [Internet]. 2021 [cited 12 October 2022];. Available from:  
  8. Sourial S, Tempest N, Hapangama D. Theories on the Pathogenesis of Endometriosis. International Journal of Reproductive Medicine [Internet]. 2014 [cited 12 October 2022];2014:1-9. Available from:  
  9. Marquardt R, Kim T, Shin J, Jeong J. Progesterone and Estrogen Signaling in the Endometrium: What Goes Wrong in Endometriosis?. International Journal of Molecular Sciences [Internet]. 2019 [cited 13 October 2022];20(15). Available from:  
  10. Endometriosis - Symptoms and causes [Internet]. Mayo Clinic. [cited 13 October 2022]. Available from:  
  11. Neidler S. Lymphatic and Circulatory Spread of Endometriosis – Endometriosis News [Internet]. Endometriosis News. [cited 13 October 2022]. Available from:  
  12. Endometriosis - Autoimmune Association [Internet]. Autoimmune Association. [cited 13 October 2022]. Available from:  
  13. Shigesi N, Kvaskoff M, Kirtley S, Feng Q, Fang H, Knight J et al. The association between endometriosis and autoimmune diseases: a systematic review and meta-analysis. Human Reproduction Update [Internet]. 2019 [cited 13 October 2022];25(4):486. Available from:  
  14. Malutan A, Simon I, Ciortea R, Mocan-Hognogi R, Dudea M, Mihu D. SURGICAL SCAR ENDOMETRIOSIS: A SERIES OF 14 PATIENTS AND BRIEF REVIEW OF LITERATURE. Medicine and Pharmacy Reports [Internet]. 2017 [cited 13 October 2022];90(4):411. Available from:

Rebecca Dion

Master of Public Health - MPH Student, Lund University, Sweden

Interested in health promotion for children and young adults. I have been working and studying in the multicultural environments of London , Paris and more recently in Lund. presents all health information in line with our terms and conditions. It is essential to understand that the medical information available on our platform is not intended to substitute the relationship between a patient and their physician or doctor, as well as any medical guidance they offer. Always consult with a healthcare professional before making any decisions based on the information found on our website.
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