What Is Endometriosis?
Endometriosis is a chronic inflammatory condition in which tissue similar to the endometrium — the lining of the uterus — grows outside the uterus. This ectopic tissue is hormonally responsive: it thickens, breaks down, and bleeds with the menstrual cycle, but cannot be shed in the normal way. The result is inflammation, scarring, adhesions (internal scar tissue binding structures together), and often significant pain.
It is one of the most common gynaecological conditions, affecting an estimated 1 in 9 women of reproductive age in Australia. Globally, it affects an estimated 190 million people. Despite its prevalence, the average time from first symptoms to diagnosis is 7–10 years — a persistent failure of awareness and clinical recognition.
Key Points
- Endometriosis affects ~1 in 9 women of reproductive age; many go undiagnosed for 7–10 years.
- Pain does not correlate with disease severity — mild disease can cause severe pain; extensive disease can be asymptomatic.
- Standard ultrasound does not reliably detect most endometriosis.
- There is no cure; treatment is aimed at managing symptoms and preserving quality of life and fertility.
- Hormonal treatments suppress but do not eradicate disease; symptoms often return when treatment stops.
- Surgery can provide meaningful relief but endometriosis recurs in 20–40% of women within 5 years.
- Fertility is affected in a significant proportion; early specialist review may be warranted for women trying to conceive.
Where Does Endometriosis Occur?
The most common sites include:
- Ovaries — endometriomas (“chocolate cysts”), which are blood-filled cysts that damage follicular reserve
- Fallopian tubes
- Peritoneum (the lining of the pelvic cavity)
- Uterosacral ligaments
- Rectovaginal septum — associated with severe deep dyspareunia and bowel symptoms
- Bowel (sigmoid colon, rectum) — causes bowel symptoms cyclical with menstruation
- Bladder and ureters — less common; causes cyclical urinary symptoms
In rare cases, endometriosis occurs outside the pelvis entirely — including the diaphragm, lungs, and surgical scars.
Symptoms
Pelvic Pain
Pelvic pain is the hallmark of endometriosis. It is often described as:
- Dysmenorrhoea — painful periods, often severe, beginning before menstrual flow and lasting throughout; not relieved by standard analgesics
- Chronic pelvic pain — non-cyclical pain persisting beyond menstruation
- Dyspareunia — pain during or after intercourse, particularly with deep penetration; particularly associated with posterior disease (uterosacral ligaments, rectovaginal deposits)
- Dyschezia — painful bowel movements, especially during menstruation
- Dysuria — painful urination, cyclical with periods, in bladder endometriosis
Pain severity does not predict disease extent. Women with minimal peritoneal deposits may have severe, debilitating pain; women with large ovarian endometriomas may have little discomfort. This poor correlation is explained by inflammation, nerve fibre ingrowth into lesions, and central sensitisation — a process by which the nervous system amplifies pain signals over time with repeated exposures.
Bowel and Bladder Symptoms
When endometriosis affects bowel or bladder, symptoms can closely mimic irritable bowel syndrome (IBS) or a chronic bladder condition, contributing to diagnostic delay:
- Bloating, cyclical worsening diarrhoea or constipation
- Rectal bleeding during menstruation (rare but pathognomonic)
- Urinary urgency, frequency, or haematuria during menstruation
If bowel or bladder symptoms worsen cyclically with periods, endometriosis should be considered even if a different diagnosis has been made previously.
Heavy Menstrual Bleeding
Endometriosis — particularly adenomyosis (endometriosis within the uterine muscle) — commonly causes heavy menstrual bleeding. This contributes to anaemia and fatigue in many affected women.
Fatigue
Chronic fatigue is common in endometriosis and is multifactorial: pain disrupts sleep; inflammation drives systemic fatigue; anaemia contributes; and the psychological burden of chronic illness compounds physical exhaustion.
Diagnostic Delay and Why It Happens
The median diagnostic delay of 7–10 years has multiple causes:
| Factor | Effect |
|---|---|
| Normalisation of period pain | Women and clinicians dismiss severe dysmenorrhoea as “normal” |
| Limited imaging sensitivity | Standard ultrasound misses most non-cystic disease |
| Overlap with IBS, IC, functional pain | Symptoms attributed to other conditions |
| Requirement for laparoscopy | Historically, definitive diagnosis required surgery |
| Dismissal of patient-reported pain | Widespread underrecognition of pain severity |
Advocacy for earlier clinical diagnosis (without mandatory surgical confirmation) is part of current guideline reform. The 2022 ESHRE Endometriosis Guideline supports initiating empirical hormonal treatment based on clinical diagnosis when laparoscopy is not immediately indicated.
Diagnosis
Clinical Diagnosis
A clinical history of pelvic pain (dysmenorrhoea, dyspareunia, dyschezia) together with a pelvic examination may be sufficient to support a clinical diagnosis and initiate treatment, without requiring surgery.
Ultrasound
- Transvaginal ultrasound (TVUS) is the first-line imaging investigation
- It can reliably detect ovarian endometriomas (chocolate cysts)
- It has limited sensitivity for peritoneal deposits and deep infiltrating endometriosis without specialist expertise
- A normal ultrasound does not exclude endometriosis
MRI
MRI is used to map deep infiltrating endometriosis (DIE), particularly before surgery. It provides better soft-tissue definition than ultrasound for bowel and bladder involvement.
Laparoscopy
Surgical laparoscopy with biopsy has historically been the “gold standard” for diagnosis. It allows direct visualisation and histological confirmation. It is now recommended when:
- Clinical diagnosis is uncertain
- Surgery is being planned for treatment
- Infertility investigations are being performed
It is no longer required before initiating empirical hormonal therapy in women with a classical symptom history.
Treatment
Hormonal Treatments
All hormonal treatments reduce oestrogen-dependent stimulation of endometriotic tissue. No hormonal treatment cures endometriosis — symptoms typically return when treatment stops.
| Treatment | How It Works | Key Notes |
|---|---|---|
| Combined OCP | Suppresses ovulation; stabilises endometrium; continuous use preferred | First-line for pain; not for women seeking pregnancy |
| Progestogens (norethisterone, desogestrel) | Suppresses endometrial activity | Effective; side effects vary; depot forms available |
| Levonorgestrel IUD (Mirena) | Local progestogen; suppresses local growth and bleeding | Strong evidence for pain and HMB; does not restore fertility |
| GnRH agonists (Zoladex, Leuprorelin) | Induce temporary menopause | Highly effective; must use add-back HRT; 6-month courses |
| GnRH antagonists (elagolix, relugolix) | Similar to agonists; no initial flare | Newer; titratable dosing; used with add-back oestrogen |
| Dienogest | Progestogen with specific endometriosis indication | Strong evidence; Europe/Australia; not US-approved |
Surgery
Surgical removal of endometriotic deposits (excision or ablation) can provide meaningful and sustained pain relief. Excision surgery — which removes deposits entirely — is generally preferred over ablation (surface destruction) for deeper disease.
Indications for surgery:
- Symptoms not adequately controlled by hormonal treatment
- Ovarian endometrioma requiring treatment (may impair fertility if untreated)
- Deep infiltrating endometriosis affecting bowel or bladder
- Infertility evaluation and management
Recurrence after conservative surgery (preserving the uterus and ovaries) is common: 20–40% within 5 years. Post-surgical hormonal treatment is often recommended to delay recurrence.
For women who have completed childbearing and have severe disease, definitive surgery (hysterectomy ± bilateral salpingo-oophorectomy) may be appropriate. Even after this, endometriosis can recur if oestrogen replacement is used.
Pain Management
In addition to hormonal treatment, pain management for endometriosis may include:
- NSAIDs (e.g., naproxen, ibuprofen) — most useful when taken before pain onset
- Nerve pain modulators — gabapentin, amitriptyline for central sensitisation
- Physiotherapy — pelvic floor therapy for women with myofascial pain or pelvic floor dysfunction as a secondary contributor
- Psychological support — CBT and pain management programmes for chronic pain
- Multidisciplinary pain clinics — for complex or refractory cases
Fertility and Endometriosis
Endometriosis affects fertility through several mechanisms:
- Ovarian damage — endometriomas reduce ovarian reserve (AMH levels)
- Pelvic adhesions — distort tubal anatomy and impair egg pickup
- Peritoneal environment — inflammatory mediators may impair sperm function and implantation
- Uterine receptivity — deep infiltrating endometriosis may impair implantation
Women with endometriosis who want to conceive should not delay seeking specialist assessment, as ovarian reserve may be declining. Options include:
- Natural conception attempts first (if anatomy is intact and reserve is adequate)
- Surgical treatment of endometriomas and pelvic adhesions before IVF
- Ovarian reserve assessment (AMH, antral follicle count) to guide urgency
- IVF — success rates are somewhat lower in women with endometriosis than age-matched controls, but the condition is not a barrier to IVF
Chronic Pain and Quality of Life
Endometriosis is a chronic illness. The impact extends beyond physical symptoms:
- Work absenteeism and presenteeism are substantial — studies estimate 10+ hours of lost productivity per week during severe episodes
- Relationship strain from dyspareunia and unpredictable pain
- Fertility-related anxiety and grief
- Rates of anxiety and depression are elevated
Psychological support, access to peer communities, and a healthcare team that acknowledges the chronic nature of the condition are important parts of comprehensive care.
Further Reading
- ESHRE Endometriosis Guideline (2022) — European Society of Human Reproduction and Embryology clinical guideline
- Endometriosis Australia — Patient Resources — Australian patient support and information
- NHS — Endometriosis — UK national guidance
- National Endometriosis Clinical Reference Group — Australian Clinical Practice Guideline — Australian federal action plan
Related Guides
- Menopause: Symptoms, Stages, and What to Expect
- Hormone Therapy for Menopause: Weighing Risks and Benefits
- Managing Chronic Back Pain — Principles of Pain Management
- Depression: What It Is and How It’s Treated
- Mental Health: An Overview
Last updated: May 2026