Endometriosis
Symptoms, Causes & Treatment
Understanding endometriosis: what it is, why it takes so long to diagnose, and the effective medical and surgical treatments available to manage pain and protect fertility.
What Is Endometriosis?
Endometriosis is a chronic condition in which tissue similar to the lining of the uterus (the endometrium) grows outside the uterus, most commonly on the ovaries, fallopian tubes, peritoneum (the tissue lining the pelvis), and the tissue between the vagina and rectum (the pouch of Douglas). Less commonly, it can affect the bowel, bladder, and, in rare cases, distant sites such as the diaphragm or lungs.
This tissue responds to hormonal changes during the menstrual cycle in the same way as the endometrium inside the uterus -- it thickens, breaks down, and bleeds with each cycle. However, because it is located outside the uterus, the blood and tissue have no way to exit the body. This leads to chronic inflammation, scarring (adhesions), and the formation of cysts (endometriomas or "chocolate cysts" on the ovaries).
Endometriosis affects approximately 1 in 10 women of reproductive age in the UK -- around 1.5 million women. Despite its prevalence, diagnosis is often significantly delayed: on average, it takes 7–8 years from the onset of symptoms to receive a diagnosis. This delay is partly because symptoms are often normalised or dismissed, and partly because definitive diagnosis has historically required surgery.
Endometriosis is a spectrum condition. Some women have minimal disease with significant symptoms, while others have extensive disease with relatively few symptoms. The severity of symptoms does not always correlate with the extent of disease found at surgery.
What Are the Symptoms of Endometriosis?
Endometriosis symptoms vary widely — from mild discomfort to debilitating chronic pain. Symptom severity does not reliably correlate with disease severity.
Pelvic pain — cyclical, worsening around periods · Painful periods (dysmenorrhoea) · Pain during or after sex (dyspareunia) · Painful bowel movements or urination during periods · Chronic pelvic pain outside of periods · Fatigue · Difficulty conceiving (infertility) · Bloating (‘endo belly’)
Acute severe pelvic pain from endometrioma rupture (emergency) · Inability to conceive after 6–12 months · Symptoms significantly affecting daily function or quality of life · Bowel or urinary symptoms during periods suggesting deep infiltrating endometriosis
Severe period pain that prevents normal daily activity is not a normal part of menstruation and warrants clinical assessment. If you develop sudden severe pelvic pain (possible endometrioma rupture or torsion), call 999 immediately.
What Causes Endometriosis?
The exact cause of endometriosis is not fully understood, but the leading theory is that menstrual blood flows backwards through the fallopian tubes into the pelvic cavity (retrograde menstruation), seeding endometrial-like tissue in abnormal locations where it becomes established due to immune dysfunction.
Endometrial tissue grows outside the uterus and responds to hormonal cycles, causing cyclical inflammation, scarring, and adhesions that produce pain and can impair fertility.
Retrograde menstruation (backflow of menstrual blood into the pelvis) may seed endometrial cells outside the uterus. Genetic susceptibility and immune dysfunction contribute to implantation.
Endometriosis causes inflammation, scarring, and adhesions around the ovaries and fallopian tubes. It is found in up to 50% of women investigated for infertility.
Endometriosis is an oestrogen-dependent condition. Higher lifetime oestrogen exposure — from early periods, late menopause, no pregnancies, or short cycles — increases disease risk and severity.
Up to 50% of women with endometriosis-associated infertility have no other identifiable fertility problem. Endometriosis impairs egg quality, embryo implantation, and tubal function through inflammatory mechanisms.
Deep infiltrating endometriosis (DIE) invades the bowel, bladder, ureter, or rectovaginal septum and causes the most severe symptoms including cyclical bowel and urinary dysfunction.
Key Risk Factors
How Is Endometriosis Diagnosed?
Endometriosis is significantly underdiagnosed — the average time from first symptoms to diagnosis is 7–8 years. Diagnosis requires a high index of suspicion based on symptoms. Empirical treatment can be started on clinical grounds. A transvaginal ultrasound can identify endometriomas but a normal scan does not exclude endometriosis. Laparoscopy remains the definitive diagnostic procedure.
How Is Endometriosis Treated?
Treatment is individualised based on symptom severity, fertility wishes, and previous treatment response. Medical management is first-line; surgery is reserved for treatment-resistant cases or when fertility surgery is indicated.
Supportive Measures
Heat (hot water bottles) provides meaningful short-term relief from endometriosis-related pelvic pain. NSAIDs (ibuprofen, naproxen) taken continuously during periods rather than waiting for pain to begin are more effective. Pelvic floor physiotherapy reduces chronic pelvic pain and dyspareunia. Maintaining regular, gentle exercise improves inflammation and mood. Dietary changes (anti-inflammatory diet, reducing processed foods) may modestly reduce symptom severity.
Managing Recurrent Endometriosis
Endometriosis is a chronic condition with a high recurrence rate after both medical and surgical treatment. Continuous hormonal suppression reduces but does not eliminate recurrence. Women who have been disease-free after surgery and then relapse should be referred back to a specialist endometriosis centre. Fertility treatment (IVF) should be considered early in women with endometriosis-related infertility who have not conceived after 6 months of trying. Multidisciplinary care — including pain management, physiotherapy, and psychological support — is important for complex cases.
When Should You Seek Help for Endometriosis?
Sudden severe pelvic pain with collapse — possible endometrioma rupture or ovarian torsion. Call 999 immediately.
Painful periods are significantly affecting your quality of life · You have chronic pelvic pain outside of periods · You have pain during sex · You have been trying to conceive for 6 months or more without success · You have already been diagnosed with endometriosis and your symptoms are worsening.
Endometriosis: Early Diagnosis & Self-Advocacy
Endometriosis cannot be prevented, but early diagnosis dramatically reduces the duration of suffering and the risk of disease progression and infertility.
Endometriosis cannot currently be prevented, but early diagnosis reduces years of suffering. Any woman with painful periods or chronic pelvic pain should seek clinical assessment without delay.
NSAIDs taken continuously from day 1 of period (not waiting for pain to peak) are significantly more effective for endometriosis pain. Ibuprofen, naproxen, or mefenamic acid are appropriate choices.
Pelvic floor physiotherapy reduces endometriosis-related dyspareunia and chronic pelvic pain by addressing myofascial trigger points and pelvic floor hypertonicity. Typically 6–8 sessions with a specialist physiotherapist.
Continuous hormonal suppression using the pill, patch, or implant — rather than cycling with monthly periods — reduces endometriosis disease activity, lesion growth, and recurrence after surgery.
An anti-inflammatory diet rich in omega-3 fatty acids (oily fish, flaxseed), vegetables, and fibre while limiting processed foods, red meat, and trans fats may reduce inflammation and symptom severity.
Stop smoking — this is the single most impactful intervention for reducing cardiac chest pain risk. Smoking cessation reduces cardiovascular risk by 50% within one year regardless of duration of prior smoking.
Speak to a Clinician About Endometriosis
Through The GP Service, a licensed clinician can assess your symptoms, commence empirical hormonal treatment, and refer you to a specialist endometriosis centre — without an extended GP wait.
Expert clinical advice, when you need it.
Endometriosis FAQs
Endometriosis affects approximately 1 in 10 women of reproductive age in the UK — around 1.5 million women. Despite this prevalence, the average time from first symptoms to diagnosis is 7–8 years. This delay occurs because period pain is often normalised, symptoms overlap with other conditions, and endometriosis requires laparoscopy for definitive diagnosis. Symptoms on their own — including severe dysmenorrhoea, deep dyspareunia, and chronic pelvic pain — are sufficient grounds for empirical treatment and specialist referral without waiting for laparoscopic confirmation.
Endometriosis is an oestrogen-dependent condition that is inactive after the menopause once oestrogen levels fall. For most women, symptoms resolve after the final period. However, deep infiltrating endometriosis and adhesions from previous disease may continue to cause problems. Women on HRT after menopause may experience recurrence of symptoms if oestrogen levels are restored. Adding a progestogen to HRT after endometriosis helps protect against reactivation.
Endometriosis significantly increases the risk of infertility but does not make pregnancy impossible for most women. Around 70% of women with mild-to-moderate endometriosis will conceive naturally. For moderate-to-severe disease, IVF success rates are similar to the general infertile population, though may require more cycles. Laparoscopic surgery to remove endometrioma or adhesions before IVF can improve outcomes in some cases. Early referral to a reproductive specialist is recommended for women with known endometriosis who are trying to conceive.
Pericarditis is inflammation of the sac surrounding the heart, typically caused by a viral infection. It produces a sharp, stabbing chest pain that is typically worse when lying flat and relieved by leaning forward. It may be associated with fever and a pericardial friction rub on examination. Treatment is with NSAIDs (ibuprofen or aspirin) and colchicine for 3 months. Rest and avoidance of strenuous exercise during treatment are important. Pericarditis must be distinguished from myocarditis and aortic dissection, both of which are more serious.
Cardiac syndrome X (also called microvascular angina) causes typical angina symptoms — chest tightness on exertion — with a normal coronary angiogram, in the absence of coronary artery narrowing. It is caused by dysfunction of small coronary blood vessels. It is more common in women, particularly postmenopausal women. Treatment includes nitrates, beta-blockers, and sometimes hormone therapy. It is often undertreated because the normal angiogram can lead to symptoms being dismissed. Referral to a cardiologist is appropriate if symptoms persist despite standard measures.
Thrush is caused by Candida fungus, and most antifungal treatments work very well for a single episode. However, recurrent thrush (four or more episodes per year) requires a different approach. This involves a longer initial course of fluconazole (weekly for 6 months as maintenance therapy) to suppress Candida, followed by gradual tapering. Underlying triggers — particularly diabetes, immunosuppression, or antibiotic use — should be identified and addressed. Topical antifungals applied to the external vulval skin alongside vaginal treatment improve outcomes in women with significant external irritation.
No. Thrush is caused by Candida fungus, not bacteria, and antibiotics are ineffective. Using antibiotics for thrush destroys protective Lactobacillus bacteria, worsening the underlying imbalance. Thrush requires antifungal treatment: fluconazole 150mg capsule (oral) or clotrimazole pessary (vaginal). If you are not sure whether you have thrush or BV, clinical assessment (pH testing and swab) will confirm the diagnosis before treatment is started. Self-diagnosing and self-treating without knowing which condition you have risks treating the wrong infection and delaying the correct treatment.
Lichen sclerosus is a chronic inflammatory skin condition affecting the vulva, causing white, thinning, fragile skin with intense itch, soreness, and changes in vulval architecture. It can be mistaken for recurrent thrush or atrophic vaginitis. It is not infectious or sexually transmitted. It is diagnosed by clinical examination and sometimes biopsy. Treatment is with potent topical corticosteroids (typically clobetasol propionate 0.05%). It requires long-term monitoring as it carries a small increased risk of vulval cancer if untreated. Any woman with persistent vulval symptoms should be examined rather than treated empirically.