She has been telling doctors about her periods since she was thirty-one. They are heavy enough that she plans her week around them, and the pain is not the cramping she remembers from her twenties but something duller and heavier, a dragging weight low in her pelvis that arrives days before the bleeding does.
She has had a scan. It was normal. She was told her periods are just heavy, offered the pill, and sent away.
She is now forty-three. Nobody has said the word adenomyosis, and there is a reasonable chance nobody will until she has a hysterectomy and a pathologist finds it in the tissue.
Your uterus has two main layers: the endometrium, the lining that thickens and sheds each month, and the myometrium, the thick muscular wall beneath it.
In adenomyosis, endometrial tissue grows down into that muscle wall where it does not belong. And because it is endometrial tissue, it behaves like endometrial tissue: it responds to your hormones, it thickens, and it tries to bleed, every month, inside the muscle.
The muscle responds by thickening and becoming inflamed. Over time the uterus enlarges and becomes globular, tender to the touch, and prone to contracting harder than it should.
That explains why the pain feels different from ordinary period pain. This is not the lining cramping to shed. It is bleeding trapped inside a muscle that cannot release it.
Adenomyosis has been described in medical literature for over 150 years, and until recently it could only be confirmed by examining a uterus after it had been removed.
That single fact shaped everything. Because the only women who got a diagnosis were the ones who had a hysterectomy, adenomyosis was classified as a condition of older women who had had several children. That was never true. It was simply who ended up on the operating table.
Imaging has changed this. Transvaginal ultrasound and MRI can now identify it in women who still have their uterus, and the picture that emerges is different: it is common, it affects younger women, and it affects women who have never been pregnant.
Estimates now put the prevalence at roughly 20 to 35 per cent of women, with one study of nearly a thousand symptomatic women finding it in 20.9 per cent. Among women being investigated for infertility, one study found 24.4 per cent, rising to 38.2 per cent in women with recurrent pregnancy loss.
Those numbers make it about as common as fibroids, and considerably more common than most women, and some doctors, assume.
Three symptoms dominate, and the combination is more telling than any one alone.
Heavy bleeding. Often progressively heavier over years. Flooding, clots, changing protection more often than seems reasonable, and periods that dictate what you can do that week.
Pain that is heavy rather than sharp. Women describe pressure, dragging, a bearing-down sensation, or a bruised feeling low in the pelvis. It frequently starts before the bleeding and can continue after it stops, which is different from the pattern of ordinary period pain.
A uterus that feels enlarged. Bloating that is not digestive, a sense of fullness or pressure, sometimes needing to pass urine more often. Some women describe looking a few months pregnant by the end of the day.
Others include pain during sex, particularly deep pain, and pain that has slowly extended beyond the period itself. Up to a third of women with adenomyosis visible on a scan have no symptoms at all, which is worth knowing if yours was an incidental finding.
Heavy and irregular periods in perimenopause covers what is expected in the transition, and this is one of the things worth excluding before accepting that explanation.
Three conditions produce overlapping symptoms, and the distinction changes what helps.
Fibroids are benign growths within the muscle wall, distinct lumps with defined edges. Adenomyosis is tissue diffusely infiltrating the muscle, with no clear boundary. Fibroids can often be removed individually; adenomyosis usually cannot, because there is nothing discrete to take out. The two frequently coexist. Fibroids and heavy periods covers them.
Endometriosis is endometrial-type tissue growing outside the uterus, on ovaries, ligaments and the pelvic lining. Adenomyosis is the same tissue growing inside the uterine wall. They are related, they often occur together, and they are not the same condition. Endometriosis and period pain covers that one.
The rough distinction women find useful: endometriosis pain is often felt across the pelvis and can be constant; adenomyosis pain is centred in the uterus and tied more tightly to the cycle.
Perimenopause also brings heavier, more erratic periods. The difference is direction and character. Perimenopausal bleeding is unpredictable, varying month to month. Adenomyosis tends to be consistently heavy and consistently painful, and it has usually been building for years before the transition began.
This is the part that matters most, because it is where most women lose years.
Transvaginal ultrasound is the first-line test, and it can identify adenomyosis when the person performing it is looking for it. A 2025 review found sensitivity around 78 per cent with specificity around 71 per cent. MRI has similar sensitivity with better specificity.
Now the sentence that should be printed on every scan report: a normal pelvic ultrasound does not rule out adenomyosis. A specialist quoted in a 2026 review put the problem plainly, noting that most radiologists rely on junctional zone thickness alone to make the call.
The features that indicate adenomyosis were formally defined in 2015 and revised in 2022, and they include a globular uterus, fan-shaped shadowing, an irregular or interrupted junctional zone, and cysts within the muscle. Recognising them requires the sonographer to be looking for them specifically, and reproducibility between operators is acknowledged as low.
So a normal scan means one of three things: you do not have adenomyosis, the scan was not looking for it, or the features were not visible on that day with that operator.
What to ask for. If your symptoms fit and your scan was normal, it is reasonable to ask for a transvaginal ultrasound specifically assessing for adenomyosis using the MUSA criteria, or a pelvic MRI. Naming the criteria changes the conversation, because it makes clear you are asking for a targeted assessment rather than a repeat of the same scan.
Ask also for a full blood count and ferritin. Years of heavy bleeding deplete iron long before anaemia appears, and low ferritin explains a great deal of the exhaustion women attribute to being busy. Iron, heavy periods and fatigue covers what the numbers mean.
Treatment aims at the two things making your life difficult: the bleeding and the pain. There is no cure short of removing the uterus, and a great deal can be done without going near that.
The hormonal coil is usually the first option offered and often the most effective. It thins the lining, substantially reduces bleeding, and eases pain for many women. It is not a small intervention to have fitted with an enlarged tender uterus, and it is worth asking about pain relief for the fitting rather than assuming you must simply endure it.
Tranexamic acid reduces bleeding when taken during the period. It is non-hormonal, taken only on the days you need it, and often under-offered.
Anti-inflammatories such as mefenamic acid reduce both bleeding and pain, and work best started a day before the period rather than once the pain has arrived.
Combined hormonal contraception or progestogens can suppress the cycle and reduce symptoms.
GnRH analogues induce a temporary menopausal state and shrink the tissue. They are usually short-term or a bridge to something else, because of the effect on bone.
Uterine artery embolisation reduces blood supply to the affected tissue and has reasonable evidence.
High-intensity focused ultrasound is newer, uses focused sound waves to destroy the tissue without surgery, and is of particular interest to women wanting to preserve fertility. Availability varies considerably.
Hysterectomy is definitive and cures it. It is the right answer for some women and should not be the first offer to a woman in her thirties.
Adenomyosis is associated with reduced fertility and higher rates of miscarriage and pregnancy complications. If you are trying to conceive, or have had recurrent losses, this is a reason to raise it specifically rather than wait. The infertility figures above are the reason.
The other question women ask is whether it ends. It does. Adenomyosis is oestrogen-driven, so symptoms typically resolve after menopause.
That is genuinely good news, and it is not a reason to wait it out if you are thirty-five. A decade of heavy painful periods is a decade of your life, and the iron loss alone is worth treating.
Go back, and go back with specifics. Vague reports of heavy painful periods are easy to absorb into normal. Concrete ones are not.
Track two or three cycles properly: how many days of bleeding, how often you change protection, whether you flood or pass clots, when the pain starts and stops, and what it stops you doing. The free hormone tracker records this in a form you can hand over.
Use the specific words. Say the pain is heavy and dragging rather than cramping. Say it starts before the bleeding. Say your abdomen feels swollen. These are the descriptions that point at adenomyosis rather than at ordinary periods.
Ask directly: could this be adenomyosis, and can we assess for it specifically?
If you have already been told a scan was normal, say so and ask what was looked for. That question is not confrontational and it is frequently the one that changes what happens next.
Adenomyosis is common, it is identifiable without surgery, and it is treatable. What it is not is well recognised, and that gap is why women spend a decade being told their periods are simply heavy.
If your periods have been getting worse for years, if the pain is heavy rather than sharp, and if your abdomen feels swollen and tender, that is a specific picture. It deserves a specific question, and a normal scan is not the end of it.
What is adenomyosis?
Endometrial tissue growing into the muscular wall of the uterus, where it responds to your hormones and bleeds each month inside the muscle. The uterus enlarges, becomes tender and contracts harder, producing heavy bleeding and a dragging pelvic pain.
How common is it?
More common than most people realise. Current estimates put it at roughly 20 to 35 per cent of women, with around 21 per cent found in one large study of symptomatic women.
How is adenomyosis different from endometriosis?
Endometriosis is the same type of tissue growing outside the uterus; adenomyosis is inside the uterine wall. They often occur together. Endometriosis pain is typically felt across the pelvis, while adenomyosis pain centres on the uterus and follows the cycle closely.
Can a normal ultrasound rule it out?
No. Sensitivity is around 78 per cent, features must be specifically looked for, and agreement between operators is low. If symptoms fit, ask for a scan assessing specifically for adenomyosis, or an MRI.
Do I need a hysterectomy?
No. Hysterectomy is the only cure but far from the only treatment. The hormonal coil, tranexamic acid, anti-inflammatories, hormonal suppression, embolisation and focused ultrasound all reduce symptoms while keeping the uterus.
Does adenomyosis affect fertility?
It is associated with reduced fertility and higher miscarriage rates. Prevalence is higher among women investigated for infertility, and higher still in those with recurrent pregnancy loss.
Will it go away after menopause?
Yes. It is oestrogen-driven, so symptoms typically resolve once oestrogen falls. That is not a reason to endure it for a decade first.
Sources: Dason ES, Maxim M, Sanders A et al., Guideline No. 437: Diagnosis and Management of Adenomyosis, J Obstet Gynaecol Can 2023;45(6):417-29 · Gallo R et al., Advances in non-invasive diagnosis of uterine adenomyosis: a narrative review, Gynecol Pelvic Med 2025;8:13 · Van den Bosch T et al., Terms, definitions and measurements to describe sonographic features of myometrium and uterine masses (MUSA consensus), Ultrasound Obstet Gynecol 2015, revised 2022 · Puente JM et al., Adenomyosis in infertile women: prevalence and the role of 3D ultrasound, Reprod Biol Endocrinol 2016;14:60 · Adenomyosis, StatPearls, NCBI Bookshelf, updated 2026 · Educational only, not medical advice.
Keep reading: Fibroids and heavy periods · Endometriosis and period pain · Heavy and irregular periods in perimenopause · Iron, heavy periods and fatigue · Painful sex · Take the free Hormone Quiz