Endometriosis: What It Is, Why It's Missed & How to Support Your Body

One in ten women has endometriosis. That's roughly 190 million people worldwide. Yet on average, it takes 7–10 years from symptom onset to diagnosis — years during which women's pain is frequently dismissed, minimised, and attributed to "normal" periods or anxiety.

I want to be direct: debilitating period pain, pain with sex, bowel symptoms around menstruation, and chronic pelvic pain are not normal. They are signals worth taking seriously, and in many cases they point to endometriosis. The fact that this condition is so consistently under-diagnosed is one of the most significant failures in women's healthcare.

This article covers everything you need to understand about endometriosis: what it is, where it grows, how it's diagnosed, what drives it, and — critically — what you can actually do to support your body.

What Endometriosis Actually Is

Endometriosis is a chronic inflammatory condition in which tissue similar to the uterine lining (endometrium) grows outside the uterus. This misplaced tissue responds to the monthly hormonal cycle — it thickens, breaks down, and tries to bleed — but because it has no way to exit the body, it causes localised inflammation, scarring (adhesions), and the formation of cysts (endometriomas on the ovaries).

Critically, the current understanding of endometriosis has shifted significantly. Rather than viewing it as a purely structural condition (tissue in the wrong place), researchers now understand it as a systemic inflammatory, immune, and neuroendocrine disease. This explains why the severity of symptoms often doesn't correlate with the extent of physical disease — some women with minimal lesions have severe pain, while others with extensive endometriosis have few symptoms.

Where Endometriosis Grows

Endometriosis can be found virtually anywhere in the pelvic cavity and beyond:

• •Ovaries — endometriomas ("chocolate cysts") form when endometrial tissue grows within the ovary and bleeds internally
• •Fallopian tubes — can affect egg transport and fertility
• •Peritoneum (the lining of the abdominal cavity) — the most common location for superficial lesions
• •Pouch of Douglas / rectovaginal septum — deep infiltrating endometriosis in this region causes severe pain with sex and bowel movements
• •Bowel and rectum — bowel endometriosis causes cyclical constipation, diarrhoea, rectal bleeding, and significant abdominal pain
• •Bladder — causes cyclical urinary symptoms including painful urination and urgency around menstruation
• •Diaphragm, lungs, and even the brain — rare but documented extra-pelvic locations that cause symptoms in unexpected areas

Staging and Why It Matters

Endometriosis is staged from I (minimal) to IV (severe) based on the extent and depth of lesions, the presence of adhesions, and ovarian involvement. However, staging has significant limitations as a guide to symptom severity or treatment planning — Stage I endometriosis can be as painful as Stage IV, because pain is driven by the inflammatory and neurological response to lesions, not just their physical extent.

More clinically useful distinctions include: superficial peritoneal endometriosis (the most common form, located on the surface of the peritoneum), ovarian endometrioma (endometriosis cysts within the ovary), and deep infiltrating endometriosis (lesions that penetrate more than 5mm into tissue, often in the rectovaginal septum, bowel, or bladder — associated with the most severe pain).

Symptoms and the Diagnostic Gap

The symptoms of endometriosis are wide-ranging and often overlap with other conditions, which is one reason diagnosis is so frequently delayed. The most characteristic symptom cluster includes:

• •Dysmenorrhea — menstrual pain that is disproportionate to what is considered "normal," doesn't respond to standard pain relief, and may be progressively worsening
• •Dyspareunia — pain with sex, particularly with deep penetration or in specific positions
• •Dyschezia — pain with bowel movements, particularly around the period
• •Chronic pelvic pain — persistent or intermittent pelvic pain not limited to menstruation
• •Heavy menstrual bleeding — often combined with dysmenorrhea
• •Cyclical bowel symptoms — constipation, diarrhoea, bloating, or rectal bleeding that worsens around menstruation
• •Fatigue — often profound, and not explained by sleep or activity level
• •Subfertility — endometriosis is found in 30–50% of women with infertility

Why Diagnosis Takes So Long

The diagnostic delay in endometriosis is one of the most studied and most troubling aspects of the condition. Several factors contribute:

Normalisation of pain: women are routinely told that severe menstrual pain is normal. Many women internalise this message and delay seeking help, or are dismissed when they do. Cultural and medical norms around period pain as something to be tolerated rather than investigated contribute significantly to delayed presentation.

Diagnostic challenges: endometriosis cannot be definitively diagnosed without surgical visualisation (laparoscopy). Ultrasound and MRI can identify endometriomas and deep infiltrating disease, but cannot reliably identify superficial peritoneal lesions — which are the most common form. A "normal" ultrasound does not rule out endometriosis.

Hormonal suppression masking symptoms: many women are put on hormonal contraceptives to "manage" their pain — effectively masking the symptoms without investigating or diagnosing the underlying cause, extending the diagnostic journey further.

Causes and Theories

The exact cause of endometriosis remains incompletely understood. Several non-mutually-exclusive theories exist:

Retrograde menstruation (Sampson's theory) — during menstruation, some menstrual blood flows backwards through the fallopian tubes into the peritoneal cavity. Most women have some retrograde menstruation, but in those with endometriosis, the endometrial cells implant and survive rather than being cleared by the immune system. This suggests immune dysfunction is central.

Coelomic metaplasia — the transformation of peritoneal cells into endometrial-like tissue, which would explain endometriosis in women who have never menstruated and in extra-pelvic locations.

Stem cell theory — endometriosis may arise from uterine stem cells that circulate and differentiate in ectopic locations.

Immune dysfunction — the immune system normally clears ectopic endometrial cells. In endometriosis, this clearance fails — research has found impaired natural killer cell activity and an altered immune environment in the peritoneal cavity. This immune failure both allows initial implantation and maintains the chronic inflammatory state that drives symptoms.

Inflammation as a Central Driver

Whatever the initial cause of endometriosis, inflammation is central to its ongoing pathology. Endometriosis lesions produce prostaglandins, cytokines, and other inflammatory mediators that cause pain, promote nerve growth into the lesions (central sensitisation), and drive further immune dysfunction in the peritoneal environment.

This is why anti-inflammatory interventions are not just symptomatic management for endometriosis — they target the underlying pathological mechanism. Reducing systemic inflammation through diet, gut healing, and stress management can meaningfully reduce the activity of endometriosis lesions and the severity of symptoms.

The gut microbiome is particularly important: research has found distinct differences in the gut microbiome of women with endometriosis compared to those without. The estrobolome — the gut bacteria involved in estrogen metabolism — is disrupted in endometriosis, contributing to the relative estrogen excess that drives lesion growth. Healing the gut is a key pillar of the functional approach to endometriosis.

What Genuinely Helps

Anti-inflammatory nutrition

A whole-food, predominantly plant-based diet rich in omega-3 fatty acids (oily fish, flaxseed, walnuts), colourful vegetables, and fibre while significantly reducing refined sugar, processed foods, red meat, alcohol, and refined seed oils — is the most impactful nutritional intervention. Research suggests that women with endometriosis who adopt an anti-inflammatory diet have significantly lower pain scores. Many women with endometriosis find that gluten and dairy elimination further reduces symptoms, likely through their effects on gut inflammation and prostaglandin production.

Gut healing

Supporting a healthy, diverse gut microbiome — through fibre diversity, fermented foods, and targeted probiotic supplementation — directly supports estrogen clearance and reduces the inflammatory burden of endometriosis. Addressing any underlying SIBO, dysbiosis, or intestinal permeability is a key part of a root-cause approach.

Supporting estrogen metabolism

Endometriosis is an estrogen-dependent condition. Supporting the liver and gut in clearing estrogen efficiently — through cruciferous vegetables, DIM, calcium d-glucarate, B vitamins for methylation, and reducing xenoestrogen exposure — can meaningfully reduce the estrogen stimulation of lesions.

Key supplements

• •Omega-3 fatty acids (EPA/DHA): 2–4 g per day; directly reduce prostaglandin synthesis and inflammatory cytokine production; one of the most evidence-supported supplements for endometriosis-related pain
• •N-acetyl cysteine (NAC): antioxidant with specific research support in endometriosis — shown in clinical studies to reduce endometrioma size and pain scores
• •Curcumin (turmeric extract): anti-inflammatory and anti-estrogenic; emerging research in endometriosis specifically; pair with piperine for absorption
• •Magnesium: reduces pain (inhibits prostaglandin synthesis and relaxes smooth muscle), supports sleep, and calms the nervous system
• •Vitamin D: plays an important role in immune regulation; deficiency is common in endometriosis and associated with worse disease activity

Surgical treatment

Excision surgery — performed by a skilled endometriosis specialist — remains the most effective treatment for reducing the disease burden of endometriosis and achieving lasting pain relief. Excision (surgical removal of lesions) is preferred over ablation (burning the surface) as it removes the full depth of lesions. Surgery is not a cure, but in the hands of a specialist, it can produce years of significantly reduced symptoms and improved quality of life. Hormonal suppression (GnRH agonists, progestins, combined pill) can manage symptoms but does not remove disease.

Living With Endometriosis

Endometriosis is a chronic condition that requires an ongoing, holistic management approach. The most successful long-term outcomes come from combining excellent specialist surgical care with consistent lifestyle and nutritional support, and from building a healthcare team that takes the condition seriously.

Pain management between flares — heat therapy, TENS machines, gentle movement, pelvic floor physiotherapy, and where appropriate, pain medicine support — is part of a comprehensive approach. So is mental health support: living with chronic pain has real psychological costs, and seeking support through therapy, peer communities (Endometriosis UK, Nancy's Nook, Endo Warriors), and patient advocacy groups is not a weakness but an important part of managing the whole person.

And fertility: endometriosis affects fertility, but it does not inevitably prevent pregnancy. Many women with endometriosis conceive naturally; others benefit from fertility treatment. A fertility-aware specialist can help you understand your individual picture and options well before fertility becomes urgent.