Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.
Adenomyosis
Obstetrics and gynaecology · UK scope · Sources checked 27 Aug 2026 · Clinical review pending
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Treat acute bleeding and pain by physiology
Adenomyosis commonly causes chronic heavy painful periods, but haemodynamic compromise, pregnancy-related pain, sudden peritonism, fever, postmenopausal bleeding or a rapidly changing mass requires urgent assessment for haemorrhage, ectopic pregnancy, infection, torsion or malignancy.
Action: Check observations and pregnancy status, quantify bleeding, obtain urgent blood count and group testing when appropriate, resuscitate and escalate through acute gynaecology or the relevant cancer pathway rather than attributing every deterioration to established adenomyosis.
Overview
Recognise adenomyosis as a myometrial cause of painful heavy bleeding, select appropriate imaging and medical treatment, and counsel accurately about uterine procedures and fertility uncertainty.
Adenomyosis is a benign uterine disorder in which endometrium-like glands and stroma are found within the myometrium, with surrounding smooth-muscle change. Disease may be diffuse throughout the uterine wall or focal as an adenomyoma. It differs anatomically from endometriosis, which lies outside the uterus, but the two conditions can coexist and share dysmenorrhoea, chronic pelvic pain and dyspareunia. Fibroids and endometrial pathology can also coexist and change bleeding management.
The cause is uncertain. Proposed mechanisms include invagination of the endometrial basalis through a disrupted junctional zone and metaplasia of embryological or adult progenitor cells within the myometrium. Repeated tissue injury and repair, inflammation, local oestrogen activity, increased vascularity and myometrial hypertrophy may produce a globular uterus, impaired contraction, heavy bleeding and pain. Pregnancy and uterine procedures are associated in observational data, but adenomyosis also occurs without either.
Aetiology
01
Junctional-zone invagination
Disruption at the endometrial–myometrial interface may allow basal endometrium to grow into muscle, followed by inflammation and smooth-muscle hypertrophy.
02
Metaplastic origin
Müllerian or adult progenitor cells within the myometrium may transform into endometrium-like tissue, helping explain disease without prior pregnancy or uterine trauma.
03
Associated factors
Age over 30, previous childbirth and uterine procedures are associated with diagnosis, but imaging now identifies disease across a broader reproductive-age population.
Pathophysiology
1
Myometrial inflammation
Ectopic glands and stroma provoke local inflammatory mediators and repeated tissue injury, contributing severe cramping, non-menstrual tenderness and sensitised uterine nerves.
2
Disordered uterine contraction
Junctional-zone disruption and hypertrophied muscle impair coordinated contraction and vascular compression, increasing dysmenorrhoea and menstrual blood loss.
3
Vascular and hormonal activity
Increased vascularity and local oestrogen-responsive signalling sustain lesion activity and bleeding, explaining why hormonal suppression can improve symptoms while it is used.
4
Diffuse or focal remodelling
Diffuse disease produces a globular uterus, while a focal adenomyoma can mimic fibroid anatomy and require expert imaging to plan treatment.
Clinical features and red flags
Classic clinical pattern
Increasingly painful heavy regular periods with a uniformly bulky tender uterus supports adenomyosis, particularly when pressure and deep dyspareunia accompany bleeding.
Ultrasound pattern
A globular asymmetric uterus with myometrial cysts, fan-shaped shadowing, echogenic islands and junctional-zone irregularity supports a myometrial rather than cavity diagnosis.
Focal adenomyoma
Localised adenomyosis can resemble a fibroid or other myometrial mass, so expert ultrasound or MRI correlation may be needed before an intervention.
Coexisting disease
Deep dyspareunia, cyclical bowel or bladder symptoms or ovarian lesions suggest concurrent endometriosis, while focal cavity bleeding can indicate a polyp or submucosal fibroid.
Anaemia phenotype
Fatigue, exertional breathlessness, palpitations, headache or pica alongside heavy bleeding should prompt blood count and iron assessment and parallel replacement.
Red flags requiring action
Syncope, tachycardia, hypotension, chest symptoms or ongoing flooding indicates clinically important blood loss and requires urgent haemorrhage assessment and stabilisation.
A positive pregnancy test with pelvic pain or bleeding redirects care to the early-pregnancy pathway because adenomyosis does not exclude ectopic pregnancy or miscarriage.
Investigations
01Pregnancy test and full blood countFirst step
Why
Redirect pregnancy-related bleeding and quantify anaemia while symptom treatment and structural assessment proceed.
Interpretation and limitations
A positive hCG changes the pathway. Haemoglobin measures consequence, not cause, and a normal count does not make heavy bleeding unimportant.
02Transvaginal pelvic ultrasound
Why
Assess the myometrium for adenomyosis, map fibroids, review the cavity and ovaries and identify coexisting endometriosis clues.
Interpretation and limitations
This is NICE's preferred imaging for HMB with substantial dysmenorrhoea or a bulky tender uterus when acceptable; report a pattern of features rather than one isolated sign.
03Transabdominal ultrasound or pelvic MRI
Why
Provide alternative or problem-solving imaging when transvaginal scanning is declined, unsuitable or inconclusive and anatomy will alter care.
Interpretation and limitations
Explain that transabdominal scanning has lower pelvic resolution and MRI is not routine initial HMB imaging; use expert interpretation to distinguish focal adenomyosis and fibroids.
04Outpatient hysteroscopy with indicated biopsy
Why
Investigate persistent intermenstrual bleeding, cavity pathology or endometrial cancer risk that adenomyosis alone does not explain.
Interpretation and limitations
Hysteroscopy evaluates the cavity, not the full myometrium. NICE advises endometrial sampling only in the context of hysteroscopy for HMB, targeted to risk.
Differential diagnosis
01
Endometriosis
Cyclical bowel or bladder symptoms, fixed organs, nodularity or an endometrioma suggest extrauterine disease, which can coexist and persist after uterine treatment.
02
Leiomyoma
An irregular enlarged uterus and discrete well-circumscribed masses favour fibroids, although focal adenomyosis and combined pathology can blur imaging appearances.
03
Endometrial or cavity disease
Persistent intermenstrual bleeding, cancer risk, polyps and submucosal fibroids require hysteroscopic assessment because myometrial imaging cannot clear the cavity.
04
Pregnancy-related bleeding
Any credible pregnancy with pain or bleeding requires hCG and pregnancy-location assessment before a benign chronic uterine diagnosis is accepted.
05
Pelvic pain syndromes
Pelvic-floor overactivity, bladder pain, bowel disease and neuropathic pain can add non-cyclical symptoms and explain incomplete response to uterine treatment.
Management
01Diagnostic routeConfirm the myometrial patternFirst stepHeavy bleeding accompanies significant dysmenorrhoea, pelvic pain or a bulky tender uterus.+
1Take a bleeding, pain and cancer-risk history, examine when indicated and obtain pregnancy testing and full blood count in parallel with treatment.
2Offer transvaginal ultrasound; if it is declined or unsuitable, discuss transabdominal ultrasound or MRI and their diagnostic limitations.
3Use hysteroscopy rather than assuming adenomyosis when persistent intermenstrual bleeding or endometrial risk points to cavity pathology.
02Medical routeMatch bleeding and pain treatment to goalsSymptoms require treatment and there is no emergency or immediate procedural indication.+
1Consider a 52 mg LNG-IUS for HMB when acceptable, after pregnancy exclusion and suitability assessment, and explain early bleeding change and the six-cycle response horizon.
Complications
01
Anaemia
Repeated heavy bleeding can cause iron depletion and anaemia with fatigue, breathlessness, palpitations, cognitive effects and reduced capacity for work and care.
02
Chronic pain and disability
Persistent dysmenorrhoea, deep dyspareunia and pelvic pain can impair sleep, mobility, intimacy and mental wellbeing and may recruit sensitisation mechanisms.
03
Fertility and pregnancy uncertainty
Adenomyosis is associated with subfertility and adverse pregnancy outcomes in observational evidence, but individual prognosis and treatment effects remain uncertain.
04
Treatment failure or recurrence
Symptoms may persist after ablation or recur after embolisation and medical suppression, leading to repeat procedures or eventual hysterectomy.
Monitoring and follow-up
Repeat full blood count according to bleeding severity and treatment response and confirm that iron deficiency or symptomatic anaemia is being corrected.
After LNG-IUS insertion, review pregnancy symptoms, pain, fever, thread change and problematic bleeding; allow up to six cycles for benefit when safe and acceptable.
For tranexamic acid, review renal function and thrombotic history, confirm use begins only with menstrual bleeding and reassess if loss remains uncontrolled after several cycles.
After uterine artery embolisation, track pain, bleeding, infection and recurrence and maintain access for further procedure discussion because symptom return is possible.
Reassess new intermenstrual, postcoital or postmenopausal bleeding, mass features or non-cyclical pain through the appropriate cavity, cancer or alternative-diagnosis pathway.
Special situations
Imaging can be sufficient clinically
Histology after hysterectomy confirms glands within muscle, but treatment does not require removal of the uterus merely to secure microscopic proof.
Hysteroscopy sees the wrong compartment
It is valuable for polyps, submucosal fibroids and targeted endometrial sampling but cannot exclude disease embedded within the myometrium.
Pain may signal coexistence
Persistent deep, bowel or bladder pain after bleeding improves can indicate concurrent endometriosis or pelvic-floor dysfunction rather than failure of the bleeding treatment.
Embolisation is not fertility-neutral
The uterus is retained, but NICE emphasises that effects on fertility and future pregnancy are uncertain and must be discussed before selection.
Ovaries need separate consent
Hysterectomy for adenomyosis does not inherently require oophorectomy; removal creates surgical menopause and changes long-term health and hormone decisions.
Common pitfalls
01
Using MRI before transvaginal ultrasound as routine initial imaging for HMB with suspected adenomyosis.
02
Assuming hysteroscopy or a normal cavity excludes myometrial adenomyosis.
03
Calling all painful heavy bleeding adenomyosis without considering pregnancy, endometriosis, fibroids and endometrial disease.
04
Removing an LNG-IUS early for expected initial irregular bleeding without counselling about the time needed for benefit.
05
Presenting uterine artery embolisation as proven to preserve fertility or to prevent all recurrence.
06
Including ovary removal automatically in hysterectomy consent for a disease located in the uterine muscle.
Practice
Two practice questions
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Question 1 of 2
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Obstetrics and gynaecologyOriginal SBA
Preferred adenomyosis imaging
A 39-year-old has increasingly painful heavy periods and examination finds a diffusely bulky tender uterus. Pregnancy testing is negative. Which imaging investigation does NICE prefer initially for suspected adenomyosis?
Sources and review status5 sources · checked 27 Aug 2026 · clinical review pending+
Sources
Sources and review status
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.
Ask about bleeding and pain as separate burdens. Heavy menstrual bleeding is defined by its adverse effect on quality of life rather than a measured volume. Record cycle timing, duration, flooding, clots, night changes, double protection, intermenstrual or postcoital bleeding and anaemia symptoms. Map dysmenorrhoea, non-menstrual pelvic pain, deep dyspareunia and pressure. Clarify pregnancy potential, fertility plans and prior uterine surgery or treatment. A symptom diary can help assess response but is not required for diagnosis.
Abdominal and bimanual examination may show a symmetrically enlarged, globular and tender uterus. A discrete irregular mass favours fibroids, while fixed retroversion or nodularity raises coexisting endometriosis. Examination can be normal and cannot distinguish all myometrial pathology. Speculum examination is appropriate for postcoital bleeding, discharge or suspected cervical disease. Obtain consent, offer a chaperone and adapt internal assessment when unacceptable or distressing.
NICE NG88 gives a clear imaging route for heavy bleeding with adenomyosis features. Offer transvaginal ultrasound when significant dysmenorrhoea or a bulky tender uterus raises suspicion, in preference to transabdominal ultrasound or MRI. Typical signs include a globular uterus, asymmetric myometrial thickening, myometrial cysts, fan-shaped shadowing, echogenic islands and an irregular or interrupted junctional zone. Reporting expertise matters and no single feature should be interpreted without the whole study.
If transvaginal scanning is declined or unsuitable, consider transabdominal ultrasound or MRI and explain their limitations. MRI can clarify uncertain or complex anatomy when the result will change a procedure, but is not the routine initial HMB investigation. Hysteroscopy inspects the cavity and may identify a polyp, submucosal fibroid or suspicious endometrium; it does not inspect most of the myometrium and is not a diagnostic test for adenomyosis. Endometrial sampling is based on bleeding pattern and cancer risk and, under NICE HMB guidance, is obtained in the context of hysteroscopy rather than blind biopsy.
Management follows the symptom target and reproductive goal. For HMB with suspected or confirmed adenomyosis, NICE recommends considering an LNG-IUS first when acceptable. Explain insertion, contraception, expulsion and perforation risks and that irregular or prolonged bleeding is common in early cycles; at least six cycles may be needed to judge benefit safely. The 52 mg system has the strongest bleeding evidence, but product licences and duration must be checked rather than assuming all intrauterine systems are interchangeable.
If an LNG-IUS is declined or unsuitable, consider tranexamic acid or an NSAID, combined hormonal contraception or cyclical oral progestogens. Tranexamic acid reduces bleeding only during use and is not contraceptive; thrombosis history and renal function are important. NSAIDs can reduce prostaglandin-mediated pain and some bleeding but bring gastrointestinal, renal, cardiovascular and pregnancy risks. Hormonal contraception may suppress pain and bleeding, with product-specific medical eligibility. Treat iron deficiency and anaemia in parallel rather than waiting for bleeding control.
Persistent severe symptoms merit specialist discussion. Endometrial ablation destroys the cavity lining but not deep myometrial disease, so pain or bleeding can persist and subsequent pregnancy is dangerous; reliable contraception and fertility completion are essential. NICE permits uterine artery embolisation for adenomyosis with ordinary governance, consent and audit because short- and medium-term symptom relief occurs in a substantial proportion. Selection should involve a gynaecologist and interventional radiologist; counselling must include non-response, recurrence, further procedures and uncertain fertility effects.
Hysterectomy removes the uterus and is definitive for uterine adenomyosis, but it is major surgery and ends the ability to carry a pregnancy. It does not require routine ovary removal: ovarian conservation or removal has separate implications for surgical menopause, bone and cardiovascular health, and possible coexisting endometriosis. Review results by the person's quality-of-life goals and re-open the diagnosis when treatment failure suggests cavity disease, fibroids, endometriosis, pelvic-floor pain or another source.
Key points
Adenomyosis is endometrium-like glands and stroma within the uterine muscle, accompanied by surrounding myometrial hypertrophy and inflammation; it is distinct from endometriosis outside the uterus but often coexists with it.
Typical features are heavy menstrual bleeding, progressively painful periods, chronic pelvic pain, deep dyspareunia and a diffusely bulky tender uterus, although some people have no symptoms.
Take bleeding impact seriously: assess flooding, clots, protection changes, anaemia symptoms, cycle regularity, intermenstrual or postcoital bleeding, pain, pressure and reproductive goals.
For heavy bleeding with significant dysmenorrhoea or a bulky tender uterus, NICE recommends transvaginal ultrasound in preference to transabdominal ultrasound or MRI; explain alternatives if internal scanning is declined or unsuitable.
Obtain a full blood count for everyone with heavy menstrual bleeding in parallel with treatment; pregnancy, cervical and endometrial testing are driven by the broader presentation rather than by adenomyosis alone.
NICE recommends considering a levonorgestrel intrauterine system as the initial HMB treatment for suspected or diagnosed adenomyosis when acceptable, with counselling that bleeding may be irregular and benefit can take at least six cycles.
Tranexamic acid
Persistent intermenstrual or postcoital bleeding, postmenopausal bleeding or endometrial cancer risk factors require cavity and endometrial assessment rather than imaging-only reassurance.
A discrete, rapidly enlarging or postmenopausal uterine mass, weight loss or constitutional symptoms should not be assumed to be benign diffuse adenomyosis.
Sudden severe pain, guarding, vomiting or fever is atypical for stable adenomyosis and requires evaluation for adnexal, infective, urinary or gastrointestinal emergencies.
05Iron studies and additional targeted tests
Why
Confirm iron depletion or investigate coagulopathy, thyroid disease and other contributors when history provides a specific indication.
Interpretation and limitations
NICE does not recommend routine ferritin, female hormone or thyroid testing for every HMB presentation; select tests from symptoms and treatment consequences.
2
If declined or unsuitable, consider tranexamic acid, an NSAID, combined hormonal contraception or cyclical oral progestogen according to contraindications and fertility plans.
3Treat iron deficiency or anaemia, record quality-of-life goals and review response before allowing prolonged ineffective therapy.
03Procedure routeCompare uterine preservation with certaintySymptoms remain severe despite appropriate medical options or the person prefers procedural management.+
1Reconfirm anatomy and discuss that ablation treats the endometrial surface, embolisation reduces uterine blood supply and hysterectomy removes the affected organ.
2For embolisation, use multidisciplinary selection and explain possible non-response, recurrence, further procedures and uncertainty about future fertility and pregnancy.
3For hysterectomy, discuss route, operative risks, recovery, irreversible loss of uterine fertility and a separate evidence-based decision about ovarian conservation.
04Treatment failureRe-open anatomy and pain mechanismsBleeding or pain persists despite an adequate, acceptable treatment trial.+
1Check adherence, device position, haemoglobin and whether bleeding, dysmenorrhoea, deep pain or non-cyclical pain was the non-responsive domain.
2Reassess for fibroids, cavity pathology, endometriosis, pelvic-floor dysfunction, bladder or bowel disease rather than assuming more severe adenomyosis alone.
3Refer for specialist imaging or shared procedural counselling and update fertility and uterine-preservation priorities.
Key medicines and prescribing safety2 treatments · regimens, roles and cautions+
NICE's preferred treatment to consider for HMB with suspected or diagnosed adenomyosis when intrauterine therapy is acceptable.
Levonorgestrel 52 mg intrauterine system
Insert one 52 mg system into the uterine cavity after excluding pregnancy and assessing infection and uterine anatomy; the cited product is licensed for heavy menstrual bleeding for 5 years.
Do not insert with pregnancy, active pelvic infection, unexplained high-risk bleeding or important cavity distortion. Discuss insertion pain, perforation, expulsion, altered bleeding and ovarian cysts; review missing threads, pregnancy symptoms, fever or persistent pain promptly.
A non-hormonal, non-contraceptive option that reduces menstrual blood loss during treatment when an LNG-IUS is declined or unsuitable.
Tranexamic acid
Once heavy menstrual bleeding starts, take 1 g orally three times daily for as long as needed up to 4 days; for very heavy loss the total may be increased but must not exceed 4 g in 24 hours.
Avoid in active or previous venous or arterial thrombosis, severe renal impairment, consumption coagulopathy and a seizure history; reduce dose for renal impairment, assess irregular bleeding first and use particular caution with combined oral contraception.
, NSAIDs, combined hormonal contraception or cyclical oral progestogens are alternatives when an intrauterine system is declined or unsuitable, selected around contraindications and fertility plans.
Uterine artery embolisation can relieve symptoms in a substantial proportion but recurrence and further procedures are possible and fertility effects are uncertain; hysterectomy is definitive uterine treatment when pregnancy is no longer desired.