Your period lasts seven days, you change a tampon every hour and your belly feels heavy and tender. Your GP calls it "a heavy cycle". Yet there can be a condition behind it that affects the muscle wall of your uterus, and it is far less well known than endometriosis: adenomyosis.
In adenomyosis, tissue that resembles your womb lining grows into the muscle layer of the uterus itself. That muscle layer becomes thickened, tender and sometimes properly painful. Research shows the condition has long been underdiagnosed, largely because a good ultrasound or MRI is needed to see it (Moawad, 2023).
I will say this straight away, because it is often explained wrongly. There is no blood test that detects adenomyosis. Blood tests do have a role with these complaints, but a different one than you might hope. Below you read exactly which.
What is adenomyosis?
Adenomyosis is a condition in which tissue resembling your womb lining grows into the myometrium, the muscle layer of your uterus. That tissue responds to your hormones each cycle and swells along with them. The muscle wall becomes thickened and inflamed, which can cause heavy periods and pain. Your uterus can become larger and more tender as a result.
Where endometriosis plays out outside your uterus, adenomyosis sits right in the middle of it.
That difference is not just a detail. It explains why the complaints feel different. With adenomyosis the heavy bleeding usually leads, with cramps that feel deep and pressing rather than sharp.
The condition is most common in women between 35 and 50, and more common in women who have given birth. It also occurs in younger women without children, so age alone tells you little.
Adenomyosis is benign. It is not cancer and it does not become cancer. It can limit your daily life considerably, and that alone is reason enough to take it seriously.
What are the symptoms of adenomyosis?
The best known symptoms of adenomyosis are heavy periods, painful cramps that often start before your period, and a pressing or bloated feeling in your lower abdomen. Many women also notice fatigue, pain during sex and bleeding between periods. Some women have no complaints at all and hear about it by chance during an ultrasound.
That last point matters. A thickened uterine wall on an ultrasound says nothing in itself about how much trouble it gives you.
The table below links each symptom to the reason it occurs. This shows these are not separate complaints, but a connected picture.
| Symptom | Why it occurs |
|---|---|
| Heavy or prolonged period | The thickened, infiltrated muscle layer contracts less well, which increases blood loss |
| Painful cramps (dysmenorrhoea) | The tissue in the muscle wall swells and bleeds along, which irritates the muscle and makes it contract |
| Pressing or bloated feeling low in your abdomen | Your uterus is enlarged and presses on your bladder and bowels |
| Fatigue and breathlessness on exertion | Prolonged heavy bleeding can deplete your iron stores (Donnez, 2022) |
| Pain during sex | The enlarged, tender uterus is touched during deep penetration |
| Bleeding between periods or spotting | The lining and the infiltrated tissue bleed irregularly |
What strikes me in the stories of women with adenomyosis is how often the bleeding gets waved away. While that is exactly the symptom that leaves a trace in your blood, and so can be measured.
Do you mainly recognise the heavy bleeding? Then read our explainer on heavy periods, causes and when to test. Has your cycle also become erratic? Then irregular periods and which hormones to test gives you more to go on.
Adenomyosis, endometriosis or a fibroid?
Adenomyosis, endometriosis and fibroids are often mixed up, because all three can cause heavy periods and pain. The difference is location. Adenomyosis sits in the muscle wall of your uterus, endometriosis outside your uterus, and a fibroid is a benign muscle lump in or on the uterine wall. They also frequently occur together.
That overlap is exactly why a good diagnosis takes so long. You can have all three at once.
This table sets the three side by side, including what blood tests do and do not say about them. I miss that last column on almost every website about this subject, while it is the question women ask us most often.
| Adenomyosis | Endometriosis | Fibroid (myoma) | |
|---|---|---|---|
| Where it sits | In the muscle layer of your uterus | Outside your uterus, for example on ovaries or the abdominal lining | In or on the uterine wall, as a muscle lump |
| Most striking complaint | Heavy bleeding with deep, pressing cramps | Pain, also outside your period | Heavy bleeding, sometimes a fuller abdomen |
| How it is seen | Internal ultrasound, an MRI if in doubt | Ultrasound, MRI and sometimes keyhole surgery | Internal ultrasound |
| What blood tests say about it | Nothing directly. They do show whether you have anaemia or low iron | Nothing directly. CA-125 can be raised, but is not usable for diagnosis | Nothing directly. They do show whether the bleeding has affected your iron |
Read our pillar on endometriosis, symptoms, diagnosis and what blood tests add if you suspect the pain sits outside your uterus. Do you suspect a muscle lump instead? Then our article on fibroids and what you can test helps you further.
How is adenomyosis diagnosed?
Adenomyosis is diagnosed with imaging, not with blood. The gynaecologist starts with an internal ultrasound, which can show a thickened or irregular uterine wall. If there is doubt an MRI follows, which images the muscle layer in more detail. The quality of the ultrasound and the experience of the examiner strongly determine what is seen (Moawad, 2023).
In the past the diagnosis could only be confirmed after the uterus had been removed. Thankfully that is outdated.
The route almost always runs through your GP, who can refer you to a gynaecologist if complaints persist. This is what the path usually looks like:
- History: your doctor asks about your cycle, your bleeding and your pain
- Physical examination: the doctor may feel an enlarged, tender uterus
- Internal ultrasound: used to look at the thickness and structure of the muscle wall
- MRI: if there is doubt, or if the ultrasound gives no clear picture
- Blood tests: not to detect adenomyosis, but to map the consequences of the bleeding
Bring something concrete to that first appointment. In practice I see that a cycle diary of two or three months makes the difference between "a heavy period" and a story your doctor can properly weigh.
Note down each day how many pads or tampons you use, whether there are clots, how many painkillers you need and whether you cancelled work or plans. Those are the details a doctor can work with.
What can blood tests add, and what can they not?
Blood tests cannot detect adenomyosis and cannot rule it out. What they do is make the consequences of the bleeding visible. Heavy periods are a known cause of iron deficiency and anaemia in women (Donnez, 2022). Blood tests also help rule out look-alikes such as an underactive thyroid, which can also cause heavy bleeding and fatigue.
This is the part almost every other website skips, so let me work it out.
Imagine your period lasts 7 days, 3 of them so heavy that you change every hour. You are tired, but you put that down to work. Your Hb can still sit neatly within the reference range at 7.6 mmol/l, while your ferritin sits at 11 µg/l and has been draining for months. That is why we prefer to measure ferritin rather than Hb alone.
Where blood tests can help you in this situation:
- Iron and ferritin: show whether the bleeding has affected your stores, even when your Hb is still normal
- Hb and the full blood count: show whether anaemia is present
- Thyroid (TSH): an underactive thyroid can also cause heavy bleeding and fatigue
- Hormones when trying to conceive: give insight into your cycle, not into the condition itself
The Anemia panel measures Hb, ferritin and the blood count in one draw, so you see what the bleeding has done to your iron. If you only want your iron store in view, look at the Iron status. Neither tells you anything about the adenomyosis itself, and we keep saying so honestly.
What a normal result means is just as important. A normal ferritin does not rule out adenomyosis. It only means your iron store is at level at that moment.
Want to know more about what a low value actually says? Then read ferritin level, normal values and what a low ferritin means.
Can adenomyosis disappear on its own?
Adenomyosis is hormone sensitive, so complaints ease for many women around menopause, when oestrogen levels fall. Before then the condition rarely disappears on its own. Treatment therefore targets the complaints rather than a cure: pain relief, hormonal therapy that reduces the bleeding, or in rare cases surgery.
That sounds bleaker than it is. Many women get their complaints well under control with the right treatment.
Which route fits you is something you decide together with your doctor. It depends on your complaints, your age and whether you still want children. Adenomyosis can affect the chance of getting pregnant, although many women with adenomyosis do have children (Abbott, 2017).
The Thuisarts.nl page on heavy bleeding and the NHG guideline on vaginal bleeding describe the steps Dutch GPs usually take. That information is free and helps you prepare for your appointment.
When should you see your GP?
See your GP if your period is so heavy that you have to change every hour, if there are large clots, if painkillers do not control your pain, or if you have become tired and breathless. Bleeding between periods and pain during sex are good reasons to get in touch too.
You do not have to prove first that it is bad enough.
In any case, get in touch with these signals:
- You have to change your pad or tampon more often than every hour
- You lose clots larger than a euro coin
- Your period lasts longer than seven days
- You are dizzy, tired or breathless on normal exertion
- You cancel work, study or plans because of your cycle
What I mainly want you to take away: heavy bleeding is not a personality trait and not bad luck. It is a symptom, and symptoms have a cause worth investigating.
Read more about uterine and ovarian complaints
Adenomyosis rarely stands alone. The complaints overlap with other benign conditions of your uterus and ovaries, and we have worked out the questions that come with them separately.
These articles help you bring your own situation into sharper view:
- Fibroids (myomas): symptoms, anaemia and what you can test
- Uterine polyp: bleeding, causes and investigation
- Ovarian cyst: types, symptoms and when investigation makes sense
- Postmenopausal bleeding: why you always get it checked
- CA-125: what this tumour marker does and does not say
Do you still have questions about your own situation after reading? Take your cycle diary to your GP and ask directly whether adenomyosis could explain your complaints.
Frequently asked questions
Can adenomyosis be detected with a blood test?
No. There is no blood test that detects or rules out adenomyosis. The diagnosis is made with an internal ultrasound and sometimes an MRI. Blood tests are useful to see whether the heavy bleeding has led to iron deficiency or anaemia, and to rule out other causes of your complaints.
What is the difference between adenomyosis and endometriosis?
In adenomyosis the tissue grows into the muscle wall of your uterus. In endometriosis similar tissue sits outside your uterus. Adenomyosis therefore more often causes heavy bleeding, endometriosis more often pain outside your period. The two regularly occur together.
Is adenomyosis dangerous?
Adenomyosis is benign and does not become cancer. The complaints can be heavy and affect your daily life, and prolonged heavy bleeding can lead to anaemia. That makes it a reason to discuss your complaints with your GP, not a reason to be afraid.
Does adenomyosis go away at menopause?
For many women complaints ease around menopause, because the tissue is hormone sensitive and oestrogen levels fall. This does not apply to everyone, and hormone therapy can affect the picture. Discuss your personal situation with your GP or gynaecologist.
References
- Moawad G, et al. Adenomyosis: an updated review on diagnosis and classification. Journal of Clinical Medicine, 2023. PMID 37510943.
- Abbott JA. Adenomyosis and abnormal uterine bleeding (AUB-A): pathogenesis, diagnosis, and management. Best Practice and Research Clinical Obstetrics and Gynaecology, 2017. PMID 27810281.
- Donnez J, et al. Uterine disorders and iron deficiency anemia. Fertility and Sterility, 2022. PMID 36182260.
- NHG. NHG guideline on vaginal bleeding. Dutch College of General Practitioners. Available via richtlijnen.nhg.org.
- Thuisarts.nl. I have heavy bleeding during my period. Dutch College of General Practitioners. Available via thuisarts.nl.
Every blood test result through Lunara includes a professional assessment by a BIG-registered doctor. For the diagnosis and treatment of adenomyosis, discuss your symptoms with your GP or gynaecologist.
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