Adenomyosis: the endometriosis inside the uterine wall

There is a moment that many women with very heavy periods know. The moment when they get a name for the first time for something that has been happening every month for years. Before, it was called: a heavy period. A sensitive uterus. Maybe stress. Afterwards it is called: adenomyosis.

That is not a small difference. A name turns a diffuse feeling into a finding. And a finding turns enduring into a decision.

Adenomyosis in brief: lining tissue inside the muscle wall

Your uterus has three layers. On the inside the lining, which builds up every menstrual cycle and is shed again. In the middle a strong muscle layer, the myometrium. On the outside a thin covering. Normally each layer stays where it belongs.

In adenomyosis it does not. Lining tissue then sits in the middle of the muscle. Not as a foreign body that migrated in from outside at some point, but as tissue that has grown across the border between lining and muscle.

Picture a brick wall. The mortar belongs between the bricks. If it starts pushing into the bricks themselves, the wall is still there. It is just no longer cleanly separated. It becomes thicker, irregular, softer in some places and harder in others. That is exactly what happens in the uterine wall.

This tissue does not stop being lining tissue. It keeps responding to the menstrual cycle, it swells, it bleeds into the muscle. The muscle answers with what it can do: it thickens, it contracts, it scars. Over years this produces a uterus that is larger, softer and more tender to pressure.

The typical picture and why it stays nameless for so long

Many women know this pattern. The period is not just heavy, it is unpredictably heavy. The pain is not a pulling ache but cramping, like a fist closing and not opening again. In between a feeling as if something in the lower abdomen were pressing downwards. Heavy. Full.

And then someone says: that just varies from woman to woman.

Which is even true. It does vary. It is just that sometimes it is also a finding.

The signs that together form a pattern

There is no single symptom that proves adenomyosis. There is a combination that makes you pay attention:

This exhaustion is where the wrong turn is taken most often. Anyone losing a lot of blood cycle after cycle loses iron. If a silent inflammation is running alongside, iron may arrive poorly even when it is taken, see iron, inflammation and the hepcidin block.

Why nobody can make the diagnosis from the conversation alone

And something else follows from this. If you bleed heavily, adenomyosis is one of several possible explanations. That is exactly why there is an international classification system for it.

There is a second reason why the symptom picture stays nameless for so long. Nobody talks about how much they bleed. There is no everyday reference value. If you have bled heavily since your first period, you consider that normal, because it is your own normal.

If the bleeding has been heavy since the very first period, a second trail belongs in the picture, and it is often missed: an inherited disorder of blood clotting, most commonly von Willebrand disease. Pointers can be frequent nosebleeds, bruises without cause, prolonged bleeding after dental work, or similar bleeding in the family. A blood test can clarify this, and it is the C in the PALM-COEIN grid.

That is why one concrete question in a consultation is often more informative than any general one. Not: is your period heavy. But: do you change more often than every two hours during the day. Do you bleed through at night. Do you have to bring a change of clothes. Are there days you do not leave the house.

Adenomyosis and endometriosis: related, but not the same

This question comes up almost every time. And the short answer is: no, it is not the same.

In endometriosis, lining-like lesions sit outside the uterus, for example on the peritoneum or on the ovaries. In adenomyosis the tissue sits within the uterine wall itself. That is all that is needed here, because endometriosis is a large topic of its own: endometriosis, an integrative look at the causes.

What matters here is the relationship between the two.

They often occur together

In the large ultrasound cohort by Naftalin and colleagues, the frequency of adenomyosis was associated in the analysis with age, with the number of previous pregnancies and with the presence of pelvic endometriosis. That does not mean one causes the other. It means they are frequently found together, and that it would be a mistake to stop looking once one of them has been found.

Both conditions share strikingly much: dependence on estrogen, a chronic inflammatory component, fibrosis and the ingrowth of new nerve fibres and vessels. These commonalities explain why treatment approaches overlap. They do not explain away the fact that these are two different conditions.

Why the distinction matters in practice

For three reasons. Adenomyosis sits in an organ that can be removed, endometriosis often does not. Heavy bleeding is typical of adenomyosis and not of endometriosis. And when you are trying to conceive, the uterus itself is affected, which is the site of implantation.

One distinction often gets lost in everyday life. If diarrhoea, bloating and cramps appear in the rhythm of the period, irritable bowel syndrome is often assumed. That may fit, but it may also be a cyclical involvement of the bowel: endometriosis and the gut as well as the menstrual cycle and digestion.

The numbers question: why everything between 1 and 70 percent gets claimed

If you search for adenomyosis, you will come across numbers that do not fit together. One page writes that around one percent of women worldwide are affected. Another names a range of 5 to 70 percent. A third writes that a third of women who are struggling to conceive have adenomyosis. These cannot all be true at the same time.

And yet all of them are true in some way. The reason for that is as simple as it is consequential.

The old gold standard was the removed organ

For decades the diagnosis of adenomyosis was made in only one way: under the microscope, on the surgically removed uterus. That is a very reliable method. It just has one catch. You only obtain it in women who have had their uterus removed.

And who has their uterus removed? Predominantly women past forty, after several births, with years of symptoms. That is exactly where the old picture of age came from.

That picture was never a biological statement. It was a mirror of the examination method. A review by Chapron and colleagues describes precisely this and adds a second uncertainty: there is no uniform depth threshold above which lining tissue in the muscle counts as adenomyosis. The most widely used cut-off is half a low-power microscopic field, about 2.5 millimetres. Others in circulation are one low-power field, about 4 millimetres, two low-power fields, about 8 millimetres, and proportions of the wall thickness, one third or one quarter. Whoever sets the line high finds less, and the authors themselves call even the most common cut-off arbitrary.

And then young women came into the picture

As soon as you stop looking only at removed organs and start using ultrasound in living women, the picture of age changes. Two studies have shown this particularly clearly.

Placed side by side, the seemingly impossible range of 1 to 70 percent becomes understandable. It describes different groups, methods and definition thresholds. Anyone quoting a single number without saying who was examined with what is passing on a number without meaning.

Ultrasound in detail: learning to read the MUSA features

This is the core of the article. If you read only one section, read this one.

Many women are handed a report form with words on it that are explained nowhere. Myometrial cysts. Irregular junctional zone. Fan-shaped shadowing. It sounds threatening because it is incomprehensible. Yet these are simply descriptions of what someone saw on a screen.

Until 2015, every practice described things differently. Then an international expert group, the MUSA group, agreed on a shared vocabulary. MUSA stands for Morphological Uterus Sonographic Assessment. In 2022 this vocabulary was revised in a structured expert procedure. The most important change: since then the features are separated into direct and indirect signs.

The uncomfortable question: how much do two examiners agree?

This paragraph absolutely belongs here, especially if you are holding two different reports.

For context: a kappa value of 1.0 means complete agreement, a value of 0 means no better than chance. Values around 0.13 count as slight agreement. That is a limitation to be taken seriously.

The reverse holds just as much. These numbers are not an argument against ultrasound, they are an argument for experience, good equipment, standardised protocols and for reading the report together with the symptoms.

What you can do yourself without learning ultrasound

You do not need to be able to assess an image. What you can do is more concrete and more useful:

MRI and telling a fibroid apart: the second look

Many women go into an MRI with an expectation. The expectation is: now we will finally see it properly. That expectation is understandable. It is just not entirely accurate where adenomyosis is concerned.

MRI has real advantages. It shows the whole pelvis at once and depicts the junctional zone particularly well. With very large uteruses, with concurrent fibroids and for surgical planning it is often indispensable.

But it is not an automatic upgrade.

The junctional zone, the key feature on MRI

The junctional zone is the innermost layer of the uterine muscle, directly next to the lining. On MRI it appears as a dark band. In adenomyosis this band becomes thicker, irregular, or it breaks off in places.

Adenomyosis or fibroid: the difference in the image

This mix-up happens often, and it has consequences. Both are changes in the muscle layer. Both can lead to heavy bleeding and a feeling of pressure. Both appear on ultrasound as an area that looks different from the rest.

They behave differently, though. A fibroid can often be shelled out deliberately because it has a border. Adenomyosis has none, it blends into the tissue. That is why uterus-preserving surgery is more difficult with it and the recurrence rate higher.

There is a special form that complicates matters further: the adenomyoma. This is a circumscribed focus of adenomyosis tissue that can look like a fibroid on the image. Even for experienced specialists, this can occasionally only be told apart clearly on the removed tissue.

Treatment routes, with an honest look at the evidence

After the diagnosis, this sentence often follows: there is not much you can do. Put that way, it is not accurate. There is quite a lot you can do. What cannot be promised is that the displaced tissue will disappear again.

That is why treatment is sorted not by the tissue but by what burdens you most. Bleeding, pain, pressure from the size, or trying to conceive. Very different routes follow from that answer.

For this whole section: all medicines named here are prescription only. And one point that is rarely said out loud: in Germany, none of these medicines is licensed specifically for the indication adenomyosis. Dienogest is licensed for endometriosis, GnRH analogues for endometriosis and fibroids, the hormonal coil for contraception and for heavy menstrual bleeding. Their use in adenomyosis is therefore off-label. That is permitted and common, but it means three things: your doctor has to inform you about it separately, reimbursement is not a given, and more of the responsibility sits with the prescriber. So ask explicitly whether the chosen medicine is licensed for your diagnosis or is being used off-label. No line here is an invitation to change, reduce or stop an existing treatment. Every adjustment belongs under medical supervision.

Hormonal routes

The idea behind them is simple. Adenomyosis is estrogen dependent. If the cyclical stimulus is dampened or the lining is quietened, that may reduce the symptoms. This addresses the driver, not the cause.

One clarification about the hormonal coil, because in integrative circles I often hear blanket rejection. For heavy menstrual bleeding, the levonorgestrel intrauterine system is the first pharmaceutical option in the British guideline NICE NG88, and in the Cochrane review it performed better than tranexamic acid. For adenomyosis specifically the evidence is thinner: in the study by Guo and colleagues cited above, pain scores from three months onwards were in fact lower with dienogest. So it can be a sensible option, it is not automatically the best one.

What belongs with this: spotting over weeks to months after insertion is common, ovarian cysts, headache, breast tenderness and mood changes occur, and the insertion itself can be painful. Contraindications such as unexplained bleeding, an acute pelvic infection or a hormone-dependent tumour need to be assessed beforehand. It is also something entirely different from the copper coil, which releases no hormones; on that there is the copper coil and how women feel.

GnRH analogues take a different route. They temporarily place the body in a state without a menstrual cycle. What belongs with this: that state can feel like an early menopause, with hot flushes, disturbed sleep, dry mucous membranes and mood changes. With longer use, bone density can decrease. That is why use is usually time limited, is often placed before a procedure, and is sometimes combined with a low-dose hormone add-back therapy. That too is a medical decision with close supervision.

The route via clotting, without hormones

Procedures that preserve the uterus

Hysterectomy, considered soberly

After complete removal of the uterus, adenomyosis cannot come back. The reason is mundane: the tissue in which the condition sits is no longer there afterwards. Important to know: if the cervix is deliberately left in place, tissue can remain there that continues to cause symptoms. So ask which variant is planned.

I deliberately describe this route neither as a threat nor as a simple solution. Not as a threat, because many women take it well informed and experience it as relief. Not as a simple solution, because it is an operation with the usual risks, because pregnancy is no longer possible afterwards and because the decision is final.

What belongs with this: if the ovaries are preserved, hormone production can continue, and menopause is not brought on directly by the operation. But the procedure is not entirely without consequences for the ovaries. Observational data suggest that ovarian function declines on average somewhat earlier after a hysterectomy than without surgery. That is not a counter-argument, it simply belongs in the conversation. Whether ovaries are removed is a separate decision with its own arguments and belongs explicitly in the conversation.

Adenomyosis and trying to conceive: what the data show and what they do not

This section is the hardest in the whole article. Not because of the studies. Because of the question behind them.

If you want a child and have just received this diagnosis, you are probably looking for a number that tells you how it will turn out. That number does not exist. I can tell you what studies have observed in groups. What that means for you, nobody can say.

That is why the most important practical sentence comes first: if you are trying to conceive and it is taking time, presenting early at a fertility centre is the right route. Time is a real factor in this topic. Nothing in this section is an argument for waiting.

One point that often goes missing: the hormonal routes from the previous section are not compatible with a current wish to conceive. The hormonal coil, dienogest and GnRH analogues suppress the cycle and therefore prevent pregnancy, and dienogest and GnRH analogues must not be used in pregnancy. Anyone who wants to become pregnant therefore plans the order differently, and that is exactly what belongs in the conversation at a fertility centre.

Why adenomyosis may make implantation more difficult is not conclusively clarified. A review by a group around Boucher, which primarily addresses implantation failure in endometriosis and explicitly includes adenomyosis, lists the mechanisms under discussion: anatomical changes, a reduced ovarian reserve, endocrine deviations, immune markers, inflammatory mediators and an altered receptivity of the lining. These mechanisms are therefore described for endometriosis and discussed for adenomyosis, not established for it. The evidence is contradictory, and the authors explicitly call for new controlled studies. That is an honest we-do-not-know-yet.

A commentary by Buggio and colleagues offers an appraisal I share: these numbers belong in a counselling conversation, not in a self-assessment at the kitchen table. Methodological weaknesses prevent definitive conclusions.

Why I also look at environment and inflammation

If you sit with me and adenomyosis is in your report, I ask things that are rarely asked in a gynaecology consultation. Whether there are damp spots in your flat. What you handle at work. How your gut is doing. Whether several systems have become louder at the same time.

I understand if that sounds like a detour. So here I explain exactly why I do it and where my reasoning ends.

The starting point: the condition responds to estrogen

That is undisputed. Adenomyosis is estrogen dependent and goes along with inflammation, fibrosis and the ingrowth of new nerves and vessels. That is how the review by Chapron and colleagues puts it. Every hormonal treatment starts exactly here.

An obvious question follows from that. If a condition responds to estrogen, what about substances from the environment that can dock on in an estrogen-like way? Those substances exist, they are called xenoestrogens: xenoestrogens in everyday life. They also exist as mould products, the best known being zearalenone: zearalenone and hormones.

The question is obvious. The answer is not.

What data exist, cleanly separated by origin

The same applies to heavy metals, and here I am particularly clear. I have found no human study linking adenomyosis with cadmium, mercury or lead. That is why no such statement appears here, not even in a weakened form. If heavy metals are a topic for you for other reasons: measuring heavy metals, blood or urine. A neighbouring topic, not an explanation of cause.

Why I still look

You could rightly ask: if the data are that thin, why do you ask about it at all?

Because I am not treating adenomyosis, I am treating a person. In the consultation, heavy bleeding rarely stands alone. There is often an exhaustion that sits deeper than the blood loss explains. When several systems become louder at the same time, it is worth looking at the shared burden, see mould symptoms, an overview.

This reasoning supports the statement that capturing inflammatory load and exposure may provide starting points for overall wellbeing. It does not support the statement that this would treat the cause of adenomyosis. I keep this distinction even when it makes the text less marketable.

Why this rarely comes up in gynaecology

I deliberately do not build a front line here, because it would be false. The gynaecological assessment is the foundation for this condition. Without ultrasound, without ruling out other causes, without the interpretation of someone who assesses uteruses every day, everything else is worthless. The environmental perspective comes on top. It does not take its place, and it is no reason to postpone a recommended assessment or an indicated operation.

That xenoestrogens and mould exposure rarely come up there has understandable reasons: different training priorities, a tight time budget per appointment, and guidelines that explicitly do not recommend this search. That reticence is well founded, and I state the reasoning in full because I consider that honest.

The paragraph that matters most to me

Environmental topics have a side effect that is talked about too rarely. It is called the urge to control.

Someone reads about plasticisers and throws out the plastic containers. Then about mould, and measures the humidity three times a day. Then eating at friends' places becomes difficult. Then restaurants. Then eating in general. What started as care turns into a narrowness that makes you unwell in its own right.

That is not a theoretical worry. The line between conscious eating and an eating disorder is fluid. If thinking about exposures takes up more space than life itself, please read eating disorders between body and mind. No accusation, a safety net.

That is why my approach stays measured. A few big levers instead of a hundred small rules. Keep the flat dry, have visible mould removed professionally: mould in the home and mycotoxins, the basics. The rest is allowed to stay relaxed. Perfection is not a goal, it is a risk.

Frequently asked questions about adenomyosis

Where this topic connects to others

Adenomyosis rarely stands alone. It hangs on your iron stores, on the way your body breaks down estrogen, on your inflammatory load and on the phase of life you are currently in. Here are the texts that take things further from this point.