Endometriosis and adenomyosis both involve tissue similar to the womb lining growing where it should not, but in different places.
In endometriosis it grows outside the uterus, on the ovaries, ligaments, bladder or bowel, whereas in adenomyosis it grows inside the muscular wall of the uterus itself.
Adenomyosis typically causes heavy bleeding and an enlarged, tender uterus - endometriosis typically causes pain spread through the pelvis.
Around a third of women with one also have the other and the treatments are not the same.
Most women reach this question because they have been given one label and the treatment has not worked as expected. That is usually the clue that something else is going on alongside it.
The distinction is not academic. It changes which scan is useful, which treatment is likely to work and what happens to your fertility.
The difference in one paragraph
Both conditions involve endometrial-type tissue growing in the wrong place and both respond to the hormonal cycle, which is why both cause pain and bleeding that peak with your period. The difference is location - endometriosis grows outside the uterus, scattered through the pelvis, whereas adenomyosis grows within the muscle of the uterine wall.
That single difference in location drives everything else: where it hurts, what shows up on a scan, which operation helps and what it does to fertility.
What is adenomyosis?
In adenomyosis, endometrial tissue grows down into the myometrium, the thick muscular wall of the uterus. Each month that trapped tissue responds to hormones, bleeds and has nowhere to go - the muscle around it becomes inflamed and thickened.
The result is a uterus that is enlarged, boggy and tender, sometimes described on a scan report as bulky or globular. It can be diffuse, spread through the wall or focal, concentrated in one area, where it is sometimes called an adenomyoma and can be mistaken for a fibroid.
Adenomyosis is more common in women in their late thirties and forties and more common in women who have had children or previous uterine surgery. Endometriosis, by contrast, often begins in the teens or twenties.
The old assumption that adenomyosis is a condition of women who have completed their families is being revised. Better imaging is finding it in younger women who have never been pregnant and it is very likely underdiagnosed in that group.
How do the symptoms differ?
There is real overlap, so no symptom on its own is decisive. The pattern is what distinguishes them.
| Feature | Endometriosis | Adenomyosis |
|---|---|---|
| Where the tissue grows | Outside the uterus: ovaries, ligaments, bladder, bowel, peritoneum | Inside the muscular wall of the uterus |
| Dominant symptom | Pain, often spread through the pelvis | Heavy bleeding, with cramping pain centred low and deep |
| Character of the pain | Sharp, stabbing or dragging. Can be one-sided. Often radiates to back or legs | Deep, heavy, central cramping. Often described as bearing down |
| Bleeding | Can be heavy, but not always | Usually heavy, prolonged, with clots. The defining feature |
| The uterus on examination | Usually normal size. May be fixed by adhesions | Enlarged, soft and tender. Often described as bulky |
| Bowel and bladder symptoms | Common where deposits sit near those organs | Less common. Mostly pressure from an enlarged uterus |
| Painful sex | Common, typically deep pain in certain positions | Can occur, usually a generalised deep ache |
| Typical age at diagnosis | 20s to 30s, though symptoms often start in the teens | Late 30s to 40s |
The most useful single question is which symptom is worse. If flooding periods are the thing wrecking your month and the pain is a deep central cramp, adenomyosis moves up the list, whereas if the pain is the dominant problem, is spread through the pelvis and comes with bowel or bladder symptoms, endometriosis moves up.
Our post on what endometriosis symptoms feel like covers that side in more detail.
How are they diagnosed differently?
This is the part that trips women up, because the test that finds one is close to useless for the other.
Diagnosing endometriosis
Ultrasound picks up endometriomas on the ovaries and can suggest deep disease, but it cannot see superficial deposits, so a normal scan does not exclude it. Laparoscopy remains the definitive test, because the deposits have to be looked at directly.
Diagnosing adenomyosis
The reverse - transvaginal ultrasound is good at adenomyosis in experienced hands, because the changes are in the wall of the uterus where the probe sits closest. Sonographers look for a bulky globular uterus, asymmetrical thickening of the walls, small cysts within the muscle and a poorly defined junctional zone. MRI is more accurate again and is used where the picture is unclear or surgery is being planned.
Laparoscopy, the definitive test for endometriosis, tells you almost nothing about adenomyosis - the disease is inside the wall, so from the outside the uterus may simply look large. Historically the only certain diagnosis came from examining the uterus after a hysterectomy, which is why adenomyosis was thought rare for so long.
The practical consequence is straightforward. A woman investigated only by laparoscopy can be told she has mild endometriosis or nothing at all, while significant adenomyosis goes unmentioned. If your bleeding is heavy and your scan was brief or done abdominally rather than internally, that is worth revisiting.
Can you have both?
Yes and it is common. Studies using MRI and ultrasound put the proportion of women with endometriosis who also have adenomyosis at somewhere between 20 and 40% depending on how it is measured.
Having both explains a pattern that comes up constantly in clinic: a woman has a laparoscopy, the endometriosis is excised, her pelvic pain improves and her periods are just as heavy as before. The operation treated one disease and left the other untouched.
If that has happened to you, it is not that the surgery failed. It is that only half the problem was addressed.
How does treatment differ?
Hormonal treatment overlaps considerably. Surgery does not overlap at all.
Where the treatments are the same
Both respond to suppressing the cycle. The combined pill, progestogens and GnRH analogues all reduce symptoms in both conditions by reducing hormonal stimulation of the tissue.
A hormonal coil is often the single most useful first-line treatment for adenomyosis - it delivers progesterone directly into the uterus, thins the lining and substantially reduces bleeding. For a woman whose main problem is flooding periods it frequently avoids the need for anything more and it is also contraception, which matters in this age group.
Coil insertion at Ovara is £420 and our post on what happens at a coil fitting covers the procedure.
Where they diverge
For endometriosis, surgery means laparoscopic excision or ablation of deposits. It is targeted, it preserves the uterus and it can be repeated.
For adenomyosis, there is no equivalent - the disease is diffusely spread through the muscle of the uterus, so there is nothing discrete to cut out. Options are:
- Hormonal coil, usually first line
- Tranexamic acid during periods to reduce blood loss
- Endometrial ablation, which destroys the lining. Helps bleeding, works less well where adenomyosis is deep and is not an option if you want a future pregnancy
- Uterine artery embolisation, the same technique used for fibroids, which reduces symptoms in a majority of women
- Hysterectomy, the only definitive cure, since the disease is in the uterus itself
That last point is the hard part of adenomyosis. Endometriosis can persist after a hysterectomy because the deposits are elsewhere, whereas adenomyosis cannot because the affected organ has gone. It is a real cure and a large decision and for a woman who has finished her family and spent a decade flooding every month it is often the right one.
Where adenomyosis sits alongside fibroids, the treatment thinking overlaps further. Our guide to the fibroid treatment options covers embolisation and hysterectomy in more depth.
Which one affects fertility more?
Both can, by different mechanisms.
Endometriosis affects fertility through distorted pelvic anatomy, damaged or blocked tubes, inflammation affecting egg and sperm and endometriomas reducing ovarian reserve. Around 30 to 40% of women with endometriosis have difficulty conceiving.
Adenomyosis affects fertility differently - the problem is implantation rather than access. An inflamed, abnormally contracting uterine wall appears to interfere with an embryo embedding and adenomyosis is associated with lower IVF implantation rates and a higher miscarriage rate.
Two practical points that are frequently missed.
First, adenomyosis is worth looking for before IVF rather than after a failed cycle. Suppressing it with GnRH analogues for 2 to 3 months before an embryo transfer improves implantation rates in women with significant disease and that is a plan you can only make if somebody has looked.
Second, neither diagnosis means you can’t conceive and most women with either condition do. If you are planning a pregnancy, our post on supporting fertility and pregnancy with endometriosis covers how the sequencing is usually approached.
Call 999 or go to A&E if you are soaking a pad or tampon every hour for more than two hours running or if you feel faint, breathless or your heart is racing with heavy bleeding. Very heavy bleeding needs treating on the day and prolonged heavy periods are a common cause of severe iron deficiency.
Arrange assessment the same week for new bleeding between periods, bleeding after sex or any bleeding after 12 months without a period. Those need investigating in their own right whichever condition you have.
Why does getting this right matter?
Three reasons, all practical.
The wrong test misses the diagnosis. A laparoscopy won’t find adenomyosis and a routine ultrasound won’t exclude endometriosis - if only one has been done, only one condition has really been looked for.
The wrong treatment wastes years. Excision surgery does nothing for adenomyosis and a hormonal coil does relatively little for deep endometriosis affecting the bowel. Both are good treatments aimed at the wrong target.
Fertility planning differs. Endometriosis surgery is often done before trying to conceive, whereas adenomyosis is usually suppressed medically before an embryo transfer instead - those are different plans on different timescales.
None of this requires certainty before treatment starts. It requires somebody to have considered both, which frequently has not happened.
What to ask at your appointment
- Was my scan transvaginal and did the sonographer specifically look at the uterine wall for adenomyosis?
- Is my uterus enlarged or bulky on examination or on the scan report?
- Given my symptoms, could both conditions be present?
- If my main problem is heavy bleeding, what is the plan for that specifically?
- If I am planning a pregnancy, does anything need treating first and in what order?
- Would an MRI add anything useful in my case?
Bring a record of 2 or 3 cycles: pain scores, how heavy the bleeding was and which days stopped you doing things. It is more useful than any single test.
Sources and further reading
- NHS - Adenomyosis
- NICE - Endometriosis: diagnosis and management (NG73)
- NICE - Heavy menstrual bleeding: assessment and management (NG88)
- Royal College of Obstetricians and Gynaecologists - Heavy periods and endometriosis patient information
Our consultant gynaecologists assess adenomyosis and endometriosis at our Chelsea clinic, with transvaginal ultrasound in the same appointment, so both conditions are considered together rather than one at a time. Most patients are seen within days. New consultation £300, combined consultation and scan £475, hormonal coil insertion £420.
Major private medical insurers accepted - please contact us to confirm your provider.
Frequently Asked Questions
What is the difference between endometriosis and adenomyosis?
Both involve tissue similar to the womb lining growing where it should not, but the location differs - endometriosis grows outside the uterus, on the ovaries, ligaments, bladder or bowel, whereas adenomyosis grows inside the muscular wall of the uterus itself.
Can you have endometriosis and adenomyosis at the same time?
Yes and it is common - between 20-40% of women with endometriosis also have adenomyosis. Having both explains why some women find their pain improves after surgery for endometriosis while their heavy bleeding does not.
How do I know if I have adenomyosis or endometriosis?
The pattern gives the strongest clue. Heavy flooding periods with deep central cramping and a bulky, tender uterus point towards adenomyosis, whereas pain spread through the pelvis, painful sex and cyclical bowel or bladder symptoms point towards endometriosis. A transvaginal ultrasound and a proper history will usually distinguish them.
Does a laparoscopy diagnose adenomyosis?
No. Adenomyosis sits inside the wall of the uterus, so it isn’t visible from the outside beyond the uterus perhaps looking enlarged - transvaginal ultrasound and MRI are the tests that find it. This is why women investigated only by laparoscopy can have adenomyosis missed entirely.
What are the symptoms of adenomyosis?
Heavy, prolonged periods often with clots, deep central cramping pain, a feeling of pressure or bearing down, an enlarged tender uterus and fatigue from iron deficiency caused by the blood loss. Symptoms typically appear in the late thirties and forties.
What does adenomyosis pain feel like?
Most women describe a deep, heavy, central cramping low in the pelvis, often with a bearing-down sensation, worst during the period. It is generally less sharp and less one-sided than endometriosis pain and more closely tied to the days of heaviest bleeding.
How is adenomyosis treated?
A hormonal coil is usually first line and often enough on its own. Other options are tranexamic acid for the bleeding, hormonal suppression, endometrial ablation, uterine artery embolisation and hysterectomy. There is no equivalent of excision surgery, because the disease is spread through the muscle rather than sitting in discrete deposits.
Is a hysterectomy the only cure for adenomyosis?
It is the only definitive cure, because the disease is in the uterus itself, however most women don’t need one. A hormonal coil, medical treatment or embolisation control symptoms well enough for the majority and hysterectomy is usually considered where those haven’t worked and the family is complete.
Does adenomyosis affect fertility?
It can. The issue is implantation rather than access: an inflamed, abnormally contracting uterine wall appears to interfere with an embryo embedding and adenomyosis is associated with lower IVF implantation rates and higher miscarriage rates. Suppressing it for 2 to 3 months before an embryo transfer improves outcomes in women with significant disease.
Which is more painful, endometriosis or adenomyosis?
Neither reliably - pain severity varies enormously in both and doesn’t track the amount of disease present. The character of the pain differs more than the intensity, with endometriosis tending to be sharper and more widely spread and adenomyosis deeper and more central.
Can adenomyosis be mistaken for fibroids?
Yes. Focal adenomyosis, sometimes called an adenomyoma, can look like a fibroid on a scan and both cause heavy periods and an enlarged uterus. The distinction matters because a fibroid can be removed surgically while adenomyosis cannot, so it is worth an experienced sonographer or an MRI where the picture is unclear.
Does adenomyosis go away after menopause?
Symptoms usually settle after menopause, because the tissue depends on oestrogen, though women taking HRT can find some symptoms persist. That doesn’t help a woman in her late thirties and waiting a decade for menopause isn’t a treatment plan.
Why did my endometriosis surgery not help my heavy periods?
Most commonly because adenomyosis is also present - excision surgery treats deposits outside the uterus and does nothing for disease within the uterine wall, which is what usually drives the heavy bleeding. That pattern is a strong reason to ask for a transvaginal ultrasound specifically looking for adenomyosis.
Do I need an MRI to diagnose adenomyosis?
Not usually - a transvaginal ultrasound performed by someone looking specifically for it is accurate in most cases. MRI is used where the ultrasound is unclear, where fibroids make interpretation difficult or where surgery is being planned.
By Kerry Archer
Medically reviewed by Mr Amer Raza, MBBS MRCOG, GMC 5205372, Consultant Gynaecologist and Medical Director, Ovara Health - September 2026
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Our consultant gynaecologists assess endometriosis and adenomyosis together at our Chelsea clinic, with transvaginal ultrasound in the same appointment rather than a separate booking. Most patients are seen within days. Major private insurance policies are accepted and no GP referral is needed.
