- All resources

Women's Health Guide

Adenomyosis

The condition that looks like endometriosis but isn't

1 in 5
women are thought to have adenomyosis, though many go undiagnosed for years
⚠
Medical disclaimer

This page provides general health information. It is not a substitute for personalised medical advice, diagnosis, or treatment. Every person's situation is different. If you have concerns about your health, please speak to your GP or a qualified healthcare professional.

Adenomyosis is a condition where the tissue that normally lines the uterus (the endometrium) grows into the muscular wall of the uterus itself. It is not the same as endometriosis, though the two conditions frequently co-exist and are often confused - even by clinicians. Where endometriosis involves tissue outside the uterus, adenomyosis is entirely within it.

The result is a uterus that is enlarged, often tender, and prone to heavy and painful periods. Adenomyosis is thought to affect around 1 in 5 women, but it remains significantly underdiagnosed. Until relatively recently it could only be confirmed after a hysterectomy - now it can be diagnosed with a good quality MRI or transvaginal ultrasound by an experienced clinician.

If you have been told your periods are heavy and your scans are normal, or if you have been treated for endometriosis without full symptom resolution, adenomyosis is worth asking about specifically.

Symptoms to know

Heavy menstrual bleeding
Often the most prominent symptom. The abnormal tissue within the uterine muscle disrupts normal contraction after a period, leading to prolonged and heavy blood loss. Passing clots, flooding, and periods lasting more than 7 days are all common.
Severe period pain (dysmenorrhoea)
Cramping that is disproportionately severe - often described as deep, griping pain that starts before the period and continues throughout. Anti-inflammatories may not fully control it.
Chronic pelvic pain
Pain that persists outside of periods, particularly a sense of pressure, heaviness or aching low in the pelvis. Not all women with adenomyosis have this, but it is common in more extensive disease.
An enlarged or tender uterus
Your GP or gynaecologist may feel this on examination - a uterus that is larger or softer than expected, sometimes described as 'boggy'. This finding on examination should prompt further investigation.
Pain during sex
Particularly deep dyspareunia - pain on deep penetration. This may reflect uterine tenderness or co-existing endometriosis.
Bloating and abdominal swelling
Often cyclical and worse around the period. An enlarged uterus can cause noticeable lower abdominal distension.
Fatigue
Frequently a downstream consequence of heavy bleeding and the iron deficiency anaemia that results. If you are exhausted and your periods are heavy, ask for your ferritin to be checked alongside a full blood count.

What actually helps

Ask specifically for adenomyosis to be considered
Many women with adenomyosis have had multiple ultrasound scans reported as normal. Standard ultrasound can miss adenomyosis unless the sonographer is specifically looking for it. If your symptoms are suggestive - heavy, painful periods, enlarged uterus - ask your clinician whether adenomyosis has been excluded, and whether an MRI or specialist transvaginal ultrasound would be appropriate.
The Mirena coil is often the first-line treatment
The levonorgestrel-releasing IUS (Mirena) is recommended by NICE guidelines as first-line management for heavy menstrual bleeding associated with adenomyosis. It thins the uterine lining, significantly reduces blood loss (by around 90% in most women), and many women also report reduced pain. It takes 3-6 months to reach full effect and is worth persisting with.
Treat iron deficiency, not just anaemia
Heavy periods from adenomyosis frequently cause iron deficiency - sometimes before the full blood count shows anaemia. Low ferritin causes fatigue, brain fog, breathlessness and hair loss. Ask your GP to check ferritin specifically. Oral iron supplements are effective, though poorly tolerated by some; IV iron is an alternative if needed before procedures.
GnRH analogues can shrink the uterus temporarily
GnRH agonists (such as Zoladex or Prostap) or the newer GnRH antagonist relugolix suppress oestrogen and can significantly reduce uterine size and symptoms. They are not a long-term solution, but are useful before procedures, or to confirm that symptoms are hormone-related. Add-back HRT is usually given alongside them to protect bone density.
Uterine artery embolisation is an option worth knowing about
UAE (uterine artery embolisation) is a minimally invasive radiology procedure that reduces blood supply to the uterus, shrinking adenomyotic tissue. It has good evidence for symptom reduction and uterine preservation. NICE guidelines supports its use. It is underutilised and worth discussing if you want to avoid surgery but medical management is insufficient.
Hysterectomy is a last resort, not a first offer
Hysterectomy is curative for adenomyosis and is an option for women who have completed their family and for whom other treatments have failed. However, it is a major operation with a significant recovery period and should only be considered after other options have been tried and discussed in full. It should never be presented as the only or obvious solution early in management.

Myths worth busting

Myth
“Adenomyosis shows up on a standard ultrasound”
Standard transvaginal ultrasound can suggest adenomyosis - features like an asymmetric or globular uterus, myometrial cysts or heterogeneous texture can all be signs - but it requires an experienced operator specifically looking for it. MRI is more sensitive and specific, particularly for diffuse adenomyosis. A normal ultrasound does not rule it out.
Myth
“Adenomyosis and endometriosis are the same thing”
They are related but distinct conditions. Endometriosis involves endometrial-like tissue outside the uterus; adenomyosis involves it within the uterine muscle. They can and frequently do co-exist - in some studies, up to 50% of women with endometriosis also have adenomyosis. But they have different appearances on imaging and may need different management approaches.
Myth
“It only affects older women who have had children”
Adenomyosis is more common in women in their 30s and 40s, but it is not exclusive to those who have had children. It has been identified in younger women and those who have never been pregnant. The association with parity is debated in the literature.
Myth
“You have to have a hysterectomy to treat it”
Hysterectomy is curative but is not the only or first-line option. The Mirena coil, hormonal suppression, and uterine artery embolisation are all effective alternatives that preserve the uterus. A stepped approach through medical and minimally invasive options should be tried first, in line with NICE guidelines guidance.

Frequently asked questions

What is adenomyosis and how is it different from endometriosis?
Adenomyosis is where endometrial-like tissue grows into the muscular wall of the uterus (the myometrium). Endometriosis is where similar tissue grows outside the uterus entirely - on the ovaries, fallopian tubes, bowel or bladder. The symptoms overlap (painful, heavy periods; pelvic pain; pain during sex) but the conditions are distinct and require different approaches on imaging. They frequently co-exist.
How is adenomyosis diagnosed?
Adenomyosis can be suspected from symptoms and examination findings (an enlarged, tender uterus). Diagnosis is made on imaging - either transvaginal ultrasound by an experienced operator, or MRI, which is more sensitive. Until recently, definitive diagnosis required histology after hysterectomy, but imaging diagnosis is now widely accepted. If you have been told your scans are normal but symptoms persist, ask about MRI specifically.
Can adenomyosis affect fertility?
The relationship between adenomyosis and fertility is an area of active research. Some studies suggest adenomyosis may impair implantation and increase miscarriage risk, particularly in women undergoing IVF. However, many women with adenomyosis conceive naturally without difficulty. If you have adenomyosis and are struggling to conceive, a referral to a specialist in reproductive medicine is appropriate.
Does adenomyosis go away after menopause?
Yes. Adenomyosis is oestrogen-dependent and typically regresses after menopause when oestrogen levels decline. Many women find that symptoms improve significantly as they approach menopause. This is also why hormonal treatments that suppress oestrogen (such as GnRH analogues or the Mirena coil) are effective at managing symptoms before menopause.
What is the best treatment for adenomyosis?
There is no single best treatment - it depends on the severity of symptoms, whether you want to preserve fertility, and what you have tried already. The stepped approach recommended by NICE guidelines starts with medical management: the Mirena coil is usually first-line for heavy bleeding, with hormonal suppression (GnRH analogues, combined pill, progestogens) also used. Uterine artery embolisation is a minimally invasive option. Hysterectomy is curative and appropriate for some women, but is not the only answer.
Can I get pregnant with adenomyosis?
Many women with adenomyosis do conceive naturally. The impact on fertility is not fully established and varies depending on the extent of disease. If you have adenomyosis and are planning to conceive, it is worth discussing this with a gynaecologist or reproductive specialist before starting fertility treatment, as some management options (like the Mirena coil or GnRH analogues) would need to be stopped first.

Sources & references

All clinical claims on this page are grounded in current evidence and published guidelines. Links open external websites.

  1. NICE NG88: Heavy menstrual bleeding - assessment and management (2018, updated 2021)
  2. NICE IPG367: Uterine artery embolisation for fibroids and adenomyosis
  3. NHS: Adenomyosis
  4. Endometriosis UK: Adenomyosis information

Last reviewed: July 2026. This page will be updated as guidelines change. If you spot an error or an outdated reference, please get in touch.

Dr Hiba Sher Khan
© 2026 Dr Hiba Sher Khan · drhiba.co.uk