Endometriosis and adenomyosis: much more than just bad periods

If you have found your way here, something brought you.

Maybe periods that have been described as a bit heavy for years, but leave you on the floor. Maybe pain in the days around your period, and at other times in your cycle too, that you have learned to plan your life around. Maybe a body that hurts when you have sex, or empty your bowels, or ovulate. Maybe the slow accumulation of being told it is normal, when you know in your bones that it is not.

Endometriosis and adenomyosis are both common, serious and often misunderstood conditions. They are not bad periods. They are not in your head. And the fact that they are so often missed has nothing to do with you.

What is endometriosis?

Endometriosis is a condition where tissue similar to the lining of the womb, the endometrium, grows in other parts of the body. It is most commonly found in the pelvis, including on the ovaries, fallopian tubes, outside of the uterus, bowel, bladder, and the tissues around them. In rarer cases, it can be found further from the pelvis, including the diaphragm, lungs, or surgical scars.

This tissue responds to the hormones of the menstrual cycle. It builds up, breaks down and bleeds. But unlike the lining of the womb, this blood has nowhere to go. Over time it can cause inflammation, scarring and adhesions, which may lead to pain, organ dysfunction and fertility difficulties.

What is adenomyosis?

Adenomyosis is when tissue similar to the lining of the womb grows into the muscular wall of the uterus itself, the myometrium. It is often described as the uterus's own version of endometriosis, but it is a distinct condition with its own clinical picture.

Like endometriosis, the misplaced tissue responds to cyclical hormones. Within the uterine wall, this typically produces a uterus that is enlarged and tender, causing heavy bleeding and pain that can be severe and chronic.

The two conditions often coexist. Many women have both. They can also occur on their own. The symptoms overlap, but the underlying problems are different, the diagnosis is different, and treatment can be too.

How common are they?

Endometriosis affects around 1 in 10 women and people assigned female at birth in the UK, approximately 1.5 million women. Adenomyosis is also estimated to affect around 1 in 10 women in the UK, though it is significantly under-diagnosed. In gynaecology clinics, prevalence rises to around 1 in 5.

Almost half of women report visiting their GP 10 or more times with symptoms before being diagnosed. Adenomyosis is even less well-recognised. Many women only receive a diagnosis after years of investigation, or alongside an endometriosis diagnosis.

The symptoms

The symptoms of endometriosis and adenomyosis often overlap, but there are some patterns worth knowing.

Why diagnosis takes so long

Several things make these conditions hard to identify quickly:

• Period pain has been so culturally normalised that women, families, schools and clinicians often do not recognise it as a symptom worth investigating.
• Standard scans and blood tests can look normal even when endometriosis is present.
• Adenomyosis was historically only diagnosable after hysterectomy. Imaging-based diagnosis is more recent and is not yet uniformly practised.
• Symptoms overlap with IBS, bladder conditions, musculoskeletal pain and mental health diagnoses, so women are often treated for these instead.
• Diagnostic delay is greater for younger women, women of colour, and women from more deprived backgrounds.

None of this means your pain is not real. It means the system has historically failed to recognise it.

How each is diagnosed

Following the November 2024 NICE update, endometriosis can be diagnosed earlier than before. A clinical suspicion of endometriosis is now enough to begin management, even before imaging.

Adenomyosis is most reliably diagnosed by:

• Transvaginal ultrasound by an experienced operator, looking for specific features in the muscle of the uterine wall.
• MRI, which is the most accurate non-invasive test.
• Symptoms and clinical examination, which usually start the process.

If you are pursuing investigation, ask for transvaginal ultrasound with a clinician experienced in identifying both conditions, and for an MRI if symptoms are significant.

Hormones, perimenopause and menopause

Both endometriosis and adenomyosis are oestrogen-driven, so the hormonal landscape matters:

What helps

There is no single right pathway. The best plan depends on your symptoms, your stage of life, your fertility plans, and what has and has not worked already.

The emotional reality

Both conditions are physically demanding and emotionally weighty. Many women describe:

• Years of feeling disbelieved, which can leave its own mark.
• Anxiety around pain flares, periods, intimacy, or what will happen next.
• Guilt about being unwell, cancelling plans, or seeming unreliable.
• Anger at the system, at the time lost, and at the years not believed.
• Grief for the body they expected, ease at work, spontaneity, relationships, intimacy, and an unfraught fertility journey.
• Loneliness, because even close people can struggle to grasp the day-to-day reality.

These responses are not dramatic. They are appropriate to a condition that has affected your body, your relationships, your ability to work and socialise and your sense of self, often for years.

When to seek help

You do not need to be in crisis. If you suspect endometriosis or adenomyosis, or have already been diagnosed and feel under supported:

• Keep a period and symptom diary for two or three cycles: pain location, severity, days, what helps, and what worsens it.
• Ask your GP specifically to consider endometriosis or adenomyosis.
• Ask for transvaginal ultrasound or an MRI by an operator experienced in identifying both.
• If you have been dismissed, you can ask for a second opinion or a referral to a BSGE-accredited specialist endometriosis centre.
• Bring written information from Endometriosis UK or NICE NG73 to your appointment if it helps you advocate.

Trusted UK resources

Frequently asked questions

What is the difference between endometriosis and adenomyosis?

Endometriosis is when tissue similar to the womb lining grows outside the uterus, on the ovaries, bowel, bladder, pelvic tissues and sometimes beyond. Adenomyosis is when similar tissue grows into the muscular wall of the uterus itself. They share many symptoms and often coexist, but they are clinically distinct and may need different treatments.

Can you have both at the same time?

Yes, and many women do. Coexistence is common, particularly in women in their 30s and 40s. The presence of one should prompt the question about the other.

How long does diagnosis usually take?

In the UK, the average time from first symptoms to a diagnosis of endometriosis is 8 years and 10 months. Adenomyosis is even less well-recognised. Persisting, asking specifically for these conditions to be considered, and seeking out experienced clinicians can shorten this.

Will menopause cure my endometriosis or adenomyosis?

Both conditions usually improve significantly after menopause because they are oestrogen-driven. However, they do not always disappear entirely, and perimenopause can be a particularly difficult phase before symptoms quieten.

Can I take HRT if I have endometriosis or adenomyosis?

Often, yes, but the choice of HRT regimen matters. Some forms can reactivate symptoms, others are well-tolerated. A menopause-informed clinician, ideally one familiar with these conditions, can help you decide.

Does endometriosis or adenomyosis cause infertility?

Both conditions are associated with fertility difficulties, although many women with either or both conditions conceive without intervention. If you are planning a pregnancy or struggling to conceive, an early conversation with a fertility specialist who understands these conditions is worth having.

Take what is useful. Leave what is not. Go gently with yourself. You have been carrying this for a long time, and you deserve to be heard.