The exact cause of endometriosis remains unknown. However, several theories suggest how it might develop. It is likely that multiple factors—including genetics, immune dysfunction, and hormonal influences—play a role.
Endometriosis is a medical condition where tissue similar to the lining of the womb (endometrial stroma and glands) grows outside the uterus. This misplaced tissue reacts to the monthly menstrual cycle, leading to inflammation, pain, and sometimes scarring.
How Common Is Endometriosis?
Endometriosis affects approximately 10% of women and people assigned female at birth during their reproductive years. That’s an estimated 190 million individuals worldwide [1].
Despite being relatively common, many people go undiagnosed for years. The average delay in diagnosis ranges from 7 to 10 years [2].
Understanding how endometriosis might develop is important in improving early recognition and treatment.
Where Endometriosis Can Develop
Endometrial-like tissue can grow in various parts of the body. Common anatomical sites include:
- Ovaries (can form cysts known as endometriomas or “chocolate cysts”)
- Fallopian tubes
- Pelvic ligaments
- Uterine lining and outer surface
- Peritoneum (lining of the abdomen)
- Bowel and bladder
- Pouch of Douglas (space behind the uterus)
In rare cases, it may appear in the diaphragm, lungs, skin, or brain.
These ectopic tissues respond to hormonal changes during the menstrual cycle, causing internal bleeding, inflammation, and scar tissue formation.
Common Symptoms
Endometriosis can present with a wide range of symptoms, including:
- Pelvic pain, especially before or during menstruation
- Pain during or after sexual intercourse
- Painful bowel movements or urination
- Heavy or irregular periods
- Fatigue and low energy
- Infertility or difficulty conceiving
Some individuals may have no symptoms, making early detection more difficult.
How Might Someone Get Endometriosis?
Several theories have been proposed, though no single cause has been definitively proven. These include:
1. Retrograde Menstruation
Menstrual blood flows backwards through the fallopian tubes into the pelvic cavity. Endometrial cells in the fluid attach to pelvic structures and begin to grow. However, many people experience retrograde menstruation without developing endometriosis, suggesting other factors are also involved.
2. Coelomic Metaplasia
Some abdominal cells may transform into endometrial-like cells—a process known as metaplasia. This could explain cases in people without menstruation, including rare occurrences in men on hormone therapy.
3. Embryonic Cell Rest Theory
Embryonic cells from development may later differentiate into endometrial tissue under hormonal influences. This theory explains occurrences in unusual locations like the brain or lungs.
4. Immune System Dysfunction
An impaired immune system might fail to clear ectopic endometrial cells. Studies suggest those with endometriosis may have altered immune responses that allow these cells to survive and implant.
5. Lymphatic and Blood Vessel Spread (Vascular Theory)
Endometrial cells may travel via lymphatic or blood vessels to distant sites, explaining rare cases in the lungs or brain.
6. Genetic Predisposition
Endometriosis can run in families. First-degree relatives are at higher risk. Genes related to immune and hormonal regulation may be involved [3].
Risk Factors
Several factors may increase the risk of developing endometriosis:
- Early onset of menstruation (before age 11)
- Short menstrual cycles (less than 27 days)
- Heavy or prolonged periods
- Family history of endometriosis
- Delayed childbearing or no childbirth history
- Low body mass index (BMI)
However, individuals without these factors may still develop the condition.
Possible Complications
If left untreated, endometriosis can lead to:
- Chronic pelvic pain
- Ovarian cysts (endometriomas)
- Infertility – affects up to 50% of those with the condition [4]
- Adhesions and scar tissue that bind organs together
- Emotional health issues such as depression or anxiety
Complications vary based on severity and location of the lesions.
Misconceptions About Causes
Myth: Tampons cause endometriosis
Fact: No evidence supports this claim.
Myth: Pregnancy cures endometriosis
Fact: Symptoms may temporarily ease, but the condition remains.
Myth: Only older women are affected
Fact: It can start during adolescence.
Seeking Medical Advice
If you experience pelvic pain, painful periods, or trouble conceiving, consult your GP. Early evaluation can help reduce the risk of complications.
Keeping a symptom diary can assist your doctor in making a prompt referral to a gynaecologist.
The cause of endometriosis is still being studied, but hormonal, genetic, and immune-related factors are strongly implicated.
Though it can’t be prevented, early diagnosis and treatment can ease symptoms and improve life quality. If you suspect endometriosis, seek timely medical advice.
References
[1] Giudice, L.C. Endometriosis: Science and Practice
[2] Vercellini, P. et al. Clinical Management of Endometriosis
[3] Bulun, S.E. Endometriosis: Pathogenesis and Treatment
[4] Rizk, B. et al. Endometriosis and Infertility: A Comprehensive Guide
