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What Is Endometriosis?
Endometriosis is a long-term condition that affects 1 in 10 women and people assigned female at birth. It happens when tissue similar to the lining of the womb, called endometrial-like tissue grows in places it shouldn’t, such as the ovaries, fallopian tubes, bladder, or bowel.
Each month, this tissue reacts to hormonal changes just like the womb lining does, it thickens, breaks down, and bleeds. But because it has nowhere to go, it causes inflammation, scarring, and pain, leading to a wide range of symptoms that can affect energy, fertility, and daily life.
Why It Takes So Long to Get Diagnosed
In the UK, it currently takes an average of 8 years and 10 months to receive a diagnosis of endometriosis (Endometriosis UK, 2024).
That’s nearly a decade of uncertainty, pain, and often being told it’s “just bad periods.”
Delays happen because symptoms often overlap with other conditions like IBS or pelvic inflammatory disease, and many people still face barriers to being taken seriously.
Efforts are underway to change this. Endometriosis UK has called for the government to reduce diagnosis times to one year or less by 2030, and initiatives like the ENDO1000 project which studies genetic and environmental factors in 1,000 women aim to improve early detection.
Read the Endometriosis UK Diagnosis Report
Common Symptoms of Endometriosis
Symptoms can vary from person to person. Some women experience excruciating pain; others have no symptoms until they try to conceive.
Common signs include:
- Pelvic pain, especially before or during your period
- Pain during or after sex
- Heavy or irregular bleeding
- Pain when opening bowels or passing urine
- Fertility problems caused by inflammation or scarring
- Brain fog and fatigue
- Bloating, constipation or diarrhoea, particularly around menstruation
Keeping a symptom diary can help spot patterns and support your discussions with a healthcare professional.
What Causes Endometriosis? Theories (and Why None Explain Everything)
There isn’t one clear cause, and that’s part of the problem.
Most classic theories are partly true but incomplete, and new evidence is challenging long-held assumptions.
1. Retrograde menstruation (period blood flowing backwards)
Why it was popular: It seemed to explain how womb lining cells could travel into the pelvis.
Why it’s not enough:
- Most women have some retrograde flow, but only a fraction develop endometriosis, so it can’t be the sole cause.
- It doesn’t explain distant lesions (like those found in the lungs or surgical scars).
- Studies suggest genetic, immune, and environmental factors must also be at play.
👉 In short: Retrograde flow may contribute, but it’s not the full picture.
2. “It’s purely genetic”
Why it’s partly true: Endometriosis tends to run in families, and genetic studies have identified certain risk variants.
But:
- These genes only explain a small fraction of risk.
- Many women with endometriosis have no family history at all.
- Genes can’t explain why lesions form in different places or why symptoms vary so widely.
👉 In short: Genetics may increase your susceptibility, but they don’t determine your fate.
3. Immune system dysfunction
Why it’s interesting: Studies show changes in immune cells and inflammation in those with endometriosis.
The problem:
- We don’t know if the immune changes are a cause or a consequence of the disease.
- Immune responses differ from person to person, making it hard to draw one simple conclusion.
👉 In short: The immune system clearly plays a role, but it’s one piece of a bigger puzzle.
4. Hormonal factors (especially oestrogen)
Why it makes sense: Endometriosis tissue grows in response to oestrogen and can even produce its own.
Why it falls short:
- Endometriosis can still occur after menopause, and symptoms can persist despite low oestrogen.
- Hormones affect symptom severity, but don’t fully explain how or why the disease starts.
👉 In short: Oestrogen fuels endometriosis, but it doesn’t light the match.
5. The new player: bacteria and the microbiome
Recent studies have found higher levels of a bacteria called Fusobacterium in people with endometriosis.
Animal studies show that treating this bacteria reduced lesions, sparking excitement about possible antibiotic-based therapies.
But:
- These studies are still small and early.
- We don’t yet know if the bacteria causes the disease or thrives because of it.
👉 In short: It’s a promising lead, not proven fact…yet.
The most realistic explanation
The best current theory is that endometriosis is multifactorial:
a mix of menstrual flow, immune response, genetics, hormones, and microbiome imbalance, all interacting over time.
This complexity is why there’s no single treatment or cure, and why management often combines hormonal, surgical, and lifestyle approaches.
How Endometriosis Is Diagnosed
Because symptoms can mimic other conditions, diagnosis often takes time.
Tests may include:
- Pelvic ultrasound or MRI to look for cysts or endometriotic lesions
- Laparoscopy, a minor surgical procedure that remains the gold standard for diagnosis
At The Female Health Doctor Clinic, we offer comprehensive assessments and can arrange advanced imaging to help reach a diagnosis faster.
Treatment Options
There’s no cure for endometriosis yet, but there are many ways to manage it effectively:
- Pain relief: Anti-inflammatories such as ibuprofen or prescription options for flare control
- Hormonal therapy: The pill, hormonal patches, or an IUD can help suppress symptoms
- Surgery: For severe cases, keyhole surgery can remove visible lesions or scar tissue
- Lifestyle support: Nutrition (such as the autoimmune protocol diet), exercise, sleep, and stress management can help reduce inflammation and improve wellbeing. You can read more about the AIP diet in our latest downloadable guide.
Common Myths About Endometriosis
🚫 “It’s just bad period pain.”
Endometriosis pain can be severe and disabling, it’s not normal or something to “just put up with.”
🚫 “You can’t have endometriosis if your periods are light.”
Pain and bleeding don’t always correlate. Light bleeders can still have significant disease.
🚫 “Pregnancy or menopause cures it.”
Symptoms may improve temporarily but often return. Hormonal changes can modify symptoms, not erase the condition.
🚫 “A hysterectomy fixes everything.”
Removing the womb may relieve some symptoms, but endometrial-like tissue can remain elsewhere in the body.
Living Well with Endometriosis
Endometriosis affects more than your body, it can influence your work, relationships, and mental health.
But with the right care, it is possible to live well and take control of your symptoms.
🩺 Track your cycle and symptoms
💬 Talk openly with your GP, specialist, or support group
🧘♀️ Nurture your wellbeing: stress, sleep, and gut health all play a role in inflammation
If you suspect you have endometriosis, don’t wait to get help. The earlier you seek assessment, the better your options.
👩⚕️ Need Specialist Support?
If you’re dealing with pelvic pain, fatigue, or possible endometriosis, our women’s health GPs can help.
We offer private consultations, advanced blood and imaging options, and tailored treatment plans to help you feel in control again.
👉 Book an appointment with The Female Health Doctor
