Endometriosis: Tissue Similar to the Womb Lining Growing Elsewhere

Endometriosis is a chronic inflammatory condition in which tissue similar to the womb lining grows outside the uterus. It can cause cyclical or persistent pelvic pain, bowel or bladder symptoms, painful sex and fertility difficulties. Symptoms, examination and imaging can support diagnosis without immediate surgery, while treatment is shaped by pain, disease location, fertility plans and personal preference.

What endometriosis is Endometriosis is a chronic condition involving tissue similar to the endometrium growing outside the uterus. The endometrium is the specialised tissue lining the inside of the womb and changing during the menstrual cycle. Endometriosis tissue resembles endometrium but is biologically different and should not be described as displaced normal womb lining. The condition is driven partly by hormones and inflammation and can affect several pelvic organs. Where endometriosis can occur Endometriosis commonly affects the pelvic lining, ovaries, ligaments supporting the uterus and tissues behind the uterus. It can involve the bowel, bladder, ureters, vagina and space between the vagina and rectum. An ovarian cyst formed by endometriosis is called an endometrioma. Less commonly, endometriosis occurs outside the pelvis, including the abdominal wall, diaphragm or chest. Hormonal responsiveness Many endometriosis lesions respond to ovarian hormones, particularly oestrogen. Their activity can change across the menstrual cycle, contributing to cyclical inflammation and pain. Lesions do not necessarily behave exactly like the womb lining or bleed predictably every month. Hormone sensitivity also varies between lesions and between different people. Inflammation Endometriosis lesions interact with immune cells, inflammatory signalling molecules, blood vessels and nearby nerves. This environment can cause swelling, pain and increased sensitivity within affected tissues. Repeated inflammation may alter pelvic nerve signalling and contribute to pain continuing beyond menstrual periods. Inflammation can also affect ovarian, tubal and pelvic function relevant to fertility. Adhesions and scarring Inflammation and previous surgery can produce bands of fibrous scar tissue called adhesions. Adhesions can make organs stick together or restrict normal movement between pelvic structures. They may contribute to pain, altered anatomy and difficulty conceiving. Rarely, extensive adhesions or bowel endometriosis can contribute to intestinal obstruction. Why the exact cause remains uncertain No single theory explains every location, age group or clinical pattern of endometriosis. The condition probably develops through several interacting biological pathways in susceptible people. Genetic factors, immune responses, hormonal signalling and tissue development mechanisms may all contribute. Theories describe possible origins rather than proven explanations for every individual case. Retrograde menstruation Retrograde menstruation means menstrual fluid travels backwards through the fallopian tubes into the pelvic cavity. Endometrium like cells within that fluid may attach, survive and contribute to lesion formation in susceptible people. Retrograde flow occurs in many people who never develop endometriosis, so it cannot explain the condition alone. It also does not fully explain endometriosis before menstruation or at distant body sites. Other leading theories Coelomic metaplasia proposes that cells lining the pelvis can transform into endometrium like tissue. Stem or progenitor cell theories propose that specialised cells travel or develop into endometriosis lesions. Lymphatic or blood vessel spread may help explain uncommon disease outside the pelvis. Surgical transfer can explain some endometriosis developing within scars after procedures involving the uterus. Genetic susceptibility Endometriosis occurs more commonly among close biological relatives of affected people. Many genetic variations probably contribute small amounts of risk rather than one gene determining the condition. Genes may influence hormone response, inflammation, tissue attachment and pain processing. A family history increases suspicion but is not required for diagnosis. Endometriosis is common but frequently missed Endometriosis affects an estimated one in ten women and people assigned female at birth during reproductive years. It can begin during adolescence and continue causing effects after reproductive years or surgery. Symptoms overlap with common bowel, bladder and gynaecological conditions, making recognition difficult. Normal examination or imaging can also create false reassurance when symptoms remain strongly suggestive. Diagnostic delay Long delays between symptom onset and diagnosis are well documented internationally. A 2026 Endometriosis UK survey reported an average UK diagnosis time of nine years and four months. This survey estimate describes respondents' experiences and should not be treated as an exact delay for every person. However, it demonstrates a persistent healthcare problem involving recognition, referral and access to specialist assessment. Normalising severe period pain Many people are told that disabling period pain is simply part of menstruation. Pain causing missed school, work, sleep, vomiting or inability to function should not be normalised. Repeated dismissal can delay investigation and teach people to minimise symptoms during appointments. Recognising abnormal impact is more useful than comparing pain tolerance between individuals. Pain cannot be measured from appearance People with severe pain may look well between episodes or during a brief consultation. They may continue working, studying or caring for others despite substantial physical cost. Pain reports should not be discounted because examination is normal or distress is not visibly expressed. A symptom diary can help demonstrate timing, impact and associated bowel, bladder or bleeding changes. Cyclical pelvic pain Pelvic pain linked repeatedly to menstruation is a characteristic endometriosis pattern. Pain can begin before bleeding, continue throughout menstruation or persist for several days afterwards. It may affect the lower abdomen, back, hips, groin or upper legs. The pattern can change over time and does not remain cyclical in every person. Dysmenorrhoea Dysmenorrhoea means painful menstruation. Endometriosis related dysmenorrhoea can be severe enough to disrupt daily activity and quality of life. Pain may be cramping, stabbing, burning, heavy or difficult to localise. Primary dysmenorrhoea is common, but progressive or disabling pain warrants assessment for secondary causes. Chronic pelvic pain Chronic pelvic pain generally means pelvic pain lasting six months or longer. Endometriosis pain can become present outside menstruation or eventually occur on most days. Inflammation, adhesions, pelvic floor dysfunction and altered nervous system processing can all contribute. Continuing pain does not necessarily mean lesions are continually growing or that surgery has failed technically. Deep dyspareunia Deep dyspareunia means pain felt deeply within the pelvis during or after penetrative sex. Pain can result from inflammation, restricted organ movement, pelvic floor tension or disease behind the uterus. The symptom can affect intimacy, relationships, sexual confidence and willingness to seek care. Assessment should be sensitive, consensual and inclusive of the person's relationships and sexual practices. Dyschezia and bowel symptoms Dyschezia means pain during bowel movements. Endometriosis can cause cyclical painful defecation, constipation, diarrhoea, bloating or rectal pressure. Symptoms often worsen around menstruation but can become non cyclical. Bowel symptoms can resemble irritable bowel syndrome, and both conditions can coexist. Rectal bleeding Cyclical rectal bleeding can occur when deep disease affects the bowel, although it is uncommon. Rectal bleeding has several other causes, including haemorrhoids, inflammatory bowel disease and colorectal disease. It therefore requires appropriate bowel assessment rather than automatic attribution to endometriosis. Persistent bleeding, weight loss or altered bowel habit may need urgent investigation through a separate pathway. Bladder and urinary symptoms Endometriosis can cause cyclical pain when passing urine, bladder pressure, frequency or urgency. Blood in the urine around menstruation can occur when the urinary tract is involved. Urinary infection, stones and bladder pain syndrome can produce overlapping symptoms. Deep disease affecting a ureter can rarely obstruct urine flow and threaten kidney function. Subfertility Subfertility means reduced ability to conceive within an expected timeframe. Endometriosis can affect fertility through inflammation, adhesions, altered tubal anatomy, ovarian involvement and other mechanisms. Many people with endometriosis conceive without fertility treatment. Disease extent alone cannot predict an individual's chance of pregnancy accurately. Endometriosis without pain Some people have extensive disease with little or no pain. Endometriosis may be identified during fertility investigation, imaging or surgery for another reason. Absence of pain does not guarantee minor disease. Equally, severe pain does not prove extensive disease. Symptoms do not reliably match disease extent Pain severity correlates poorly with the amount or stage of endometriosis seen during surgery. Small superficial lesions can accompany severe pain, while extensive deep disease can cause few symptoms. Nerve involvement, inflammation, lesion location, adhesions and pain sensitisation influence symptoms differently. Treatment decisions should therefore not be based on surgical stage alone. Staging systems Several systems classify endometriosis according to lesion location, depth, adhesions and anatomical effects. The revised American Society for Reproductive Medicine system uses stages one to four. Other systems describe deep disease or fertility related anatomy in different ways. A reader does not need to understand these systems to understand symptoms, treatment choices or personal impact. Staging does not grade suffering Stage one disease does not mean that pain is trivial. Stage four disease does not mean that pregnancy is impossible or symptoms must be severe. Staging can help document surgical findings and communicate anatomy between specialists. It should not be used to validate or invalidate a person's experience. Quality of life impact Endometriosis can disrupt education, employment, exercise, sleep, sex, relationships and family planning. Unpredictable pain and bleeding can make travel and social activity difficult. Repeated healthcare encounters without answers can produce frustration, mistrust and loss of confidence. Treatment should address the person's life goals rather than focusing only on visible lesions. Psychological impact Chronic pain and diagnostic delay are associated with anxiety, low mood, distress and social isolation. Psychological support does not imply that pain is imaginary or caused by personality. Pain, sleep disruption and uncertainty can affect emotional wellbeing through understandable biological and social pathways. Severe hopelessness or thoughts of self harm require direct mental health support alongside gynaecological care. Clinical assessment begins with history NICE recommends suspecting endometriosis from characteristic symptoms and their effect on daily life. History covers pain timing, menstruation, sexual symptoms, bowel and bladder changes and fertility plans. Previous treatments, operations, contraception, pregnancy possibility and family history are relevant. The clinician also considers other conditions rather than forcing every symptom into one diagnosis. A pain and symptom diary A diary can record menstruation, pain location, bowel or bladder symptoms, medication and missed activities. It can reveal cyclical patterns that are difficult to remember during one appointment. A diary supports communication but is not required before referral or treatment. People should not be asked to prove their pain repeatedly before receiving assessment. Abdominal examination Abdominal examination can assess tenderness, masses, scars and other causes of pain. A normal abdominal examination does not exclude endometriosis. Sudden guarding, marked tenderness or instability suggests an acute abdominal condition requiring urgent assessment. Examination findings must be interpreted alongside symptoms and pregnancy possibility. Pelvic examination With informed consent, pelvic examination can assess tenderness, restricted uterine movement, pelvic masses or nodularity. A pelvic examination may be normal even when endometriosis is present. It should not be performed without consent or when it would be inappropriate or excessively distressing. An abdominal examination remains appropriate when internal examination is declined or unsuitable. First line ultrasound NICE recommends offering transvaginal ultrasound to all people with suspected endometriosis, even when examination is normal. The scan can identify ovarian endometriomas, deep endometriosis and other pelvic conditions. It can also help guide referral and surgical planning. A transabdominal scan can be offered when transvaginal scanning is declined or unsuitable. What transvaginal ultrasound involves A narrow ultrasound probe is introduced gently into the vagina with consent. The procedure should be explained beforehand, and consent can be withdrawn at any time. A chaperone and trauma informed adjustments should be available according to preference and local policy. The scan may be uncomfortable but should not be continued through unacceptable pain without discussion. A normal ultrasound does not exclude endometriosis Superficial peritoneal lesions can be too small or subtle for routine ultrasound detection. Imaging quality also depends on equipment, operator training and the disease location. NICE explicitly advises not excluding endometriosis because examination, ultrasound or MRI is normal. Ongoing characteristic symptoms still justify treatment, referral or further investigation. Specialist ultrasound and MRI Specialist transvaginal ultrasound or pelvic MRI can assess suspected deep endometriosis and map its extent. MRI may be useful when initial ultrasound is inconclusive, unsuitable or when complex anatomy requires further mapping. NICE allows either specialist ultrasound or MRI for suspected deep disease in secondary care. Both should be planned and interpreted by professionals with specialist gynaecological imaging expertise. What imaging can show Imaging can identify endometriomas, deep nodules, adhesions and involvement of bowel, bladder or ureters. It helps specialists plan whether colorectal, urological or advanced laparoscopic expertise may be needed. Imaging cannot measure pain intensity or identify every superficial lesion. A scan report should be interpreted within the full clinical presentation. Blood tests and CA125 There is no blood test that confirms or excludes endometriosis. NICE advises not using CA125 to diagnose the condition. Blood tests may instead assess anaemia, infection, pregnancy or other differential diagnoses. A normal blood result does not make persistent cyclical pain unexplained or unimportant. The changing role of laparoscopy Laparoscopy is keyhole surgery allowing direct inspection of the pelvis under general anaesthesia. It is not required before beginning empirical pain treatment or hormonal treatment in many cases. Imaging and clinical assessment can now establish sufficient evidence for many management decisions. However, current NICE guidance still advises considering laparoscopy when suspicion remains, even after normal ultrasound or MRI. When laparoscopy may be considered Laparoscopy may help when diagnosis remains uncertain and symptoms persist despite appropriate treatment. It may also be used when direct visualisation will guide surgical management or fertility related decisions. Treatment can sometimes be performed during the same procedure when consent has been obtained beforehand. The risks and possible finding of no visible endometriosis should be discussed before surgery. A negative laparoscopy A systematic normal laparoscopy performed by a clinician trained in recognising endometriosis makes visible disease less likely. Microscopic disease can occasionally be missed, and pain may still have another genuine cause. A negative procedure should lead to a broader pain assessment rather than dismissal. Pelvic floor dysfunction, adenomyosis, bladder pain, bowel disorders and neuropathic pain may require attention. Biopsy A surgeon may biopsy suspicious tissue during laparoscopy for laboratory examination. Histology can support the diagnosis but a negative biopsy does not always exclude endometriosis. The appearance and location of lesions can vary considerably. Unexpected or atypical tissue may require biopsy to exclude another condition. Differential diagnosis Conditions overlapping with endometriosis include adenomyosis, fibroids, pelvic inflammatory disease and ovarian cysts. Irritable bowel syndrome, inflammatory bowel disease, bladder pain syndrome and urinary infection can cause similar symptoms. Pelvic floor dysfunction, musculoskeletal pain and nerve related pain may contribute independently or alongside endometriosis. Pregnancy related complications must be considered whenever pregnancy is possible. Adenomyosis Adenomyosis involves endometrium like tissue within the muscular wall of the uterus. It can cause painful heavy periods, pelvic pressure and an enlarged tender uterus. Adenomyosis and endometriosis can occur together. Ultrasound or MRI can sometimes support diagnosis, while treatment options overlap partly but are not identical. Irritable bowel syndrome Irritable bowel syndrome can cause abdominal pain, bloating, constipation and diarrhoea. Symptoms may fluctuate with stress, food and menstruation. Cyclical painful bowel movements and deep pelvic pain increase suspicion of endometriosis, but do not prove it. Treating one condition should not prevent assessment for the other when symptoms persist. Pelvic inflammatory disease Pelvic inflammatory disease is infection and inflammation of the upper reproductive tract. It can cause pelvic pain, abnormal discharge, pain during sex, bleeding and fever. Untreated infection can damage fertility and requires antibiotic treatment. Fever, discharge or sexual infection risk should not be attributed automatically to endometriosis. Initial pain relief NICE recommends discussing a short trial of paracetamol, an NSAID or both for endometriosis related pain. NSAIDs include medicines such as ibuprofen and naproxen and reduce prostaglandin related inflammation. They can cause stomach, kidney, cardiovascular or asthma related problems in susceptible people. Persistent pain despite initial analgesia should prompt reassessment rather than indefinite unsupervised dose escalation. Analgesia is one part of care Pain medicines can reduce symptoms without altering endometriosis lesions directly. Some people need additional treatment for neuropathic pain, pelvic floor spasm or severe chronic pain. Long term opioid treatment carries dependence, tolerance, constipation and overdose risks and is not a routine solution. A pain specialist can help when ordinary analgesia and disease directed treatment are insufficient. Hormonal treatment principles Hormonal treatments suppress ovulation, menstruation or hormonal stimulation of lesions. They can reduce pain and bleeding but do not permanently remove the underlying tendency to endometriosis. Symptoms can recur when treatment stops. Choice depends on contraindications, adverse effects, bleeding preferences, fertility plans and previous response. Treatment can begin before surgery NICE allows hormonal treatment for suspected or confirmed endometriosis. A person does not need laparoscopic confirmation before receiving an appropriate therapeutic trial. Clinical response can support symptom management but does not prove or disprove the diagnosis. Failure of one hormonal option does not exclude endometriosis. Combined hormonal contraception Combined hormonal contraception contains oestrogen with a progestogen. It can be taken cyclically or continuously to reduce menstruation and endometriosis related pain. It is unsuitable for some people with clotting risk, certain migraines, cardiovascular disease or other contraindications. It prevents pregnancy while being used and is not appropriate when actively trying to conceive. Progestogen treatment Progestogens reduce endometrial activity and can suppress menstruation and lesion stimulation. Options include tablets, injections, implants and the levonorgestrel releasing intrauterine system. Bleeding changes, mood effects, acne, breast symptoms or weight concerns can influence acceptability. Different progestogens and delivery methods can produce different individual experiences. Hormonal treatment and later fertility NICE advises explaining that hormonal treatment reduces pain without permanently harming later fertility. Normal fertility potential usually resumes after reversible treatment is stopped, although timing varies by method. Hormonal suppression does not improve spontaneous pregnancy rates while conception is being attempted. Treatment decisions therefore change when immediate fertility is the main priority. GnRH agonists Gonadotrophin releasing hormone agonists initially stimulate and then suppress ovarian hormone production. They create a temporary low oestrogen state that can reduce endometriosis pain. Hot flushes, vaginal dryness, mood change and loss of bone density can occur. Treatment duration, contraindications and monitoring require specialist supervision. Add back therapy Add back therapy uses small amounts of oestrogen, progestogen or both alongside strong ovarian suppression. It aims to reduce hot flushes, bone loss and other low oestrogen adverse effects while maintaining symptom control. The regimen is selected according to the medicine and the person's clinical risks. Add back therapy does not mean that the primary endometriosis treatment has stopped working. GnRH antagonists GnRH antagonists suppress ovarian hormones without the initial stimulation associated with agonists. NICE recommends selected oral antagonist regimens after previous medical or surgical treatment within their licensed criteria. Some products incorporate hormonal add back treatment, while others require it to be prescribed alongside. These are specialist options rather than first treatment for every person with suspected endometriosis. Monitoring hormonal treatment Review considers pain, bleeding, function, adverse effects and whether the treatment fits current goals. Blood pressure, bone health, migraine, clotting risk and mood may require attention depending on the medicine. Treatment should be changed when adverse effects outweigh benefit. People should receive clear advice about contraception because some endometriosis medicines are not reliable contraceptives by themselves. Surgical treatment Surgery can remove or destroy visible lesions, release adhesions and treat ovarian endometriomas. Most procedures are performed laparoscopically by keyhole surgery. Techniques include excision, which cuts disease out, and ablation, which destroys its surface. The approach depends on lesion location, surgeon expertise, fertility plans and risks to surrounding organs. Excision and ablation Excision removes a lesion and can provide tissue for histology. Ablation destroys visible superficial disease using energy. Evidence does not support one technique as universally superior for every lesion and clinical situation. Deep disease generally requires advanced surgical expertise rather than simple superficial ablation. Surgery for deep endometriosis Deep endometriosis can involve the bowel, bladder, ureter or tissues close to major nerves and vessels. Complex operations may require gynaecological, colorectal and urological surgeons working together. Potential benefits must be weighed against bowel, bladder, nerve, fertility and stoma related risks. NICE recommends referral to a specialist endometriosis service for suspected or confirmed deep disease. Surgery for an endometrioma An endometrioma is an endometriosis cyst within an ovary. Cystectomy removes the cyst wall and can reduce recurrence compared with simple drainage. However, ovarian surgery can remove healthy tissue or reduce ovarian reserve. Size, pain, imaging features, previous surgery and fertility treatment plans influence the decision. Hysterectomy Hysterectomy removes the uterus and may be considered for additional indications such as adenomyosis or heavy bleeding. It does not automatically cure endometriosis because lesions can remain outside the uterus. When hysterectomy is chosen, visible endometriosis should be discussed and treated where appropriate during the same operation. The irreversible loss of pregnancy potential and possible ovarian decisions require detailed informed consent. Removing the ovaries Removing both ovaries causes surgical menopause and reduces ovarian hormone production substantially. It can reduce recurrence risk but does not guarantee complete pain resolution. Immediate consequences include hot flushes, bone loss, cardiovascular effects and sexual symptoms. The decision requires specialist discussion of age, disease, menopause treatment and personal priorities. Surgery is not a guaranteed cure Surgery can produce major and lasting benefit, but symptoms or lesions can recur. Pain can persist because of adhesions, nerve sensitisation, pelvic floor dysfunction or another coexisting condition. Repeat surgery can create additional adhesions and may threaten ovarian reserve. The benefits and cumulative harms of repeated procedures require careful review. Hormonal treatment after surgery When pregnancy is not being attempted immediately, hormonal treatment can prolong symptom benefit after excision or ablation. Combined hormonal contraception or a progestogen may reduce recurrence of pain and lesions. The choice should reflect contraindications and individual tolerance. Postoperative suppression should not delay desired fertility without an informed discussion. When fertility is a priority Management should include a fertility specialist when endometriosis related subfertility is present. The team considers age, ovarian reserve, semen assessment, tubal function, disease location and duration of trying. Hormonal suppression does not improve spontaneous conception while it prevents ovulation or pregnancy. Surgery or assisted conception may be considered according to the complete fertility picture. Fertility focused surgery Laparoscopic excision or ablation with adhesiolysis can improve spontaneous pregnancy chances in selected superficial disease. Surgery for deep disease has less certain fertility benefit and carries greater complexity. Endometrioma surgery may improve access or reduce pain but can lower ovarian reserve. Decisions should avoid assuming that every visible lesion must be removed before fertility treatment. Assisted conception Assisted conception can include intrauterine insemination or in vitro fertilisation, depending on circumstances. IVF may bypass some effects of tubal damage or distorted pelvic anatomy. Endometriosis can affect ovarian response and treatment planning but does not make IVF inevitably unsuccessful. Eligibility and timing depend on age, fertility factors, previous treatment and local commissioning criteria. Chronic pain management Persistent pelvic pain often requires more than repeated surgery or increasing analgesia. A multidisciplinary approach can include gynaecology, pain medicine, physiotherapy, psychology and primary care. The aim is to reduce pain impact, improve sleep and restore valued activity while continuing disease specific care. This approach validates pain rather than suggesting that symptoms are psychological. Pelvic floor physiotherapy Persistent pain can cause protective tightening and poor coordination of pelvic floor muscles. This can worsen painful sex, bowel symptoms and pain during examination. A specialist pelvic health physiotherapist can assess muscle function and teach relaxation or rehabilitation strategies. Internal assessment or treatment should occur only with specific informed consent. Pain sensitisation Repeated pain can make peripheral nerves and the central nervous system increasingly responsive. Ordinary movement, bowel filling or touch may then provoke disproportionate pain. This process is called sensitisation and can coexist with active lesions. Treating sensitisation does not deny the original tissue disease or inflammatory cause. Everyday management Heat, pacing, gentle movement and planned rest can help some people manage symptom flares. Regular meals and constipation management may reduce additional pelvic pressure. No specific diet has been proven to cure endometriosis. Restrictive diets should not create malnutrition, guilt or delay evidence based treatment. Work and education Endometriosis can cause unpredictable absence, reduced concentration and difficulty sitting or standing for long periods. Reasonable adjustments can include flexible scheduling, remote participation, rest access and time for appointments. People should not need to disclose intimate clinical details beyond what is necessary for support. Medical treatment and practical adjustments can proceed together. Relationships and intimacy Pain during sex can create fear, avoidance and relationship strain. Partners may misunderstand reduced sexual activity as rejection. Open communication, alternative forms of intimacy, pelvic floor treatment and psychosexual support may help. Consent remains essential, and nobody should be encouraged to continue painful sexual activity. Adolescents and young people Endometriosis can begin soon after menstruation starts. Repeated school absence, vomiting, faintness or inability to function during periods warrants assessment. Young people should not be told they are too young to have endometriosis. Treatment, examination and referral should be age appropriate and involve the young person directly. Symptoms around menopause Symptoms often improve when ovarian hormone production declines, but this is not universal. Adhesions, nerve sensitisation or residual lesions can continue causing symptoms after menopause. New postmenopausal bleeding or pelvic symptoms require investigation for other conditions. Previous endometriosis should not be assumed to explain every new symptom indefinitely. Follow up Follow up depends on symptoms, treatment, fertility plans and disease complexity. People with deep disease or larger endometriomas may need specialist surveillance or planned review. New bowel, bladder or acute pain symptoms require reassessment rather than waiting for routine follow up. The care plan should state who to contact when symptoms change. Sudden severe pelvic pain Endometriosis usually causes recurrent or chronic pain rather than one abrupt catastrophic episode. Sudden severe unilateral pain with nausea or vomiting can indicate ovarian torsion, cyst rupture or internal bleeding. A known endometrioma does not make sudden pain safe to manage at home automatically. Emergency assessment is needed because ovarian blood supply or circulatory stability may be threatened. Pregnancy related emergencies Pelvic pain or bleeding during possible pregnancy requires pregnancy assessment. An ectopic pregnancy can cause one sided pain, shoulder tip pain, dizziness, collapse or internal bleeding. Endometriosis does not protect against ectopic pregnancy or explain away pregnancy related warning signs. Call emergency services for collapse, severe weakness or signs of shock. Bowel obstruction Severe adhesive or bowel endometriosis can rarely obstruct the intestine. Warning signs include severe abdominal pain, increasing distension, repeated vomiting and inability to pass stool or wind. Partial obstruction can fluctuate, while complete obstruction can deteriorate quickly. These symptoms require urgent hospital assessment rather than laxatives or routine outpatient review. Urinary obstruction Deep endometriosis can rarely narrow a ureter and damage a kidney, sometimes with limited symptoms. Flank pain, blood in the urine, fever or reduced urine output requires prompt assessment. Imaging showing ureteric involvement requires specialist endometriosis and urology planning. Kidney protection can take priority even when pelvic pain is manageable. The central safety message Endometriosis should be suspected from characteristic symptoms and functional impact rather than pain severity alone. Transvaginal ultrasound is first line imaging, but normal imaging does not exclude superficial disease. Laparoscopy is not required before all treatment, although NICE still recommends considering it when diagnostic uncertainty persists. Sudden severe pain, pregnancy related warning signs or symptoms of bowel obstruction require urgent assessment.

Endometriosis is a chronic hormone responsive inflammatory condition whose symptoms do not reliably match the amount of disease visible at surgery. Diagnosis begins with careful history and ultrasound, while treatment is individualised around pain, disease location, fertility plans, quality of life and safety.