What Is Adenomyosis? Symptoms, Causes & Treatment

Quick Facts

• Adenomyosis occurs when tissue from the uterine lining grows into the muscle wall of the uterus.
• It commonly causes heavy menstrual bleeding, pelvic pain and bloating.
• Symptoms often overlap with endometriosis and fibroids.
• It is frequently under-diagnosed despite being relatively common.

What Is Adenomyosis?

Adenomyosis is a gynaecological condition where tissue like the lining of the uterus (the endometrium) grows into the muscular wall of the uterus (the myometrium).

Adenomyosis affects the uterus itself, specifically the muscular wall (myometrium), rather than occurring outside the uterus as seen in endometriosis.

While it shares similarities with endometriosis, adenomyosis is a separate condition -and can be just as painful and disruptive.

Although it can affect women at any reproductive age, adenomyosis is most commonly diagnosed in women in their 30s and 40s, particularly those who have had children.

That said, we now know it can occur earlier – and may be contributing to symptoms long before diagnosis.

What Happens in the Body in Adenomyosis

In a healthy menstrual cycle, the endometrial lining thickens in response to hormones and sheds during menstruation (the bleed).

In adenomyosis, endometrial-like tissue becomes embedded within the uterine muscle.

Each month, this tissue still responds to hormonal signals – swelling and breaking down – but because it’s trapped within the muscle wall, it can’t shed normally.

The presence of this tissue triggers a local inflammatory response, which contributes to pain, swelling and changes in uterine structure over time.

This leads to:

• Chronic uterine inflammation
• Thickening of the uterine walls
• Increased uterine pressure and tenderness
• Heightened pain signalling from the pelvis

Over time, the uterus may become enlarged, heavy, and increasingly sensitive -contributing to both physical discomfort and systemic fatigue.

Common Symptoms of Adenomyosis

Symptoms vary widely, but may include:

• Heavy or prolonged periods (menorrhagia)
• Severe menstrual cramps (dysmenorrhoea)
• Chronic pelvic pain or pressure
• Pain during or after sex
• Bloating or a sensation of pelvic heaviness
• Fatigue and low energy (often linked to blood loss and inflammation)

Importantly, some people have no obvious symptoms at all.

In these cases, adenomyosis may only be identified during investigations for fertility concerns, recurrent miscarriage, or unexplained pelvic pain.

How Is Adenomyosis Diagnosed?

Adenomyosis is frequently under-diagnosed – often confused with fibroids, endometriosis, or dismissed as “normal” period pain.

Diagnosis may involve:

• Pelvic examination (to assess uterine size and tenderness)
• Transvaginal ultrasound (looking for characteristic changes in the uterine muscle)
• MRI, which offers the most detailed imaging when diagnosis is unclear

Historically, adenomyosis was only confirmed after hysterectomy.

Thankfully, this is no longer necessary, and imaging advances now allow for diagnosis while preserving fertility.

Treatment & Management Options

There is no single “cure” for adenomyosis — but symptoms can often be managed effectively.

Treatment options may include:

• Hormonal support (e.g. hormonal IUDs, oral contraceptives, GnRH analogues)
• Anti-inflammatory medications (NSAIDs)
• Tranexamic acid to reduce heavy bleeding
• Surgical options in severe or refractory cases (e.g. endometrial ablation or hysterectomy)

The right approach depends on:

• Symptom severity
• Age and hormonal stage
• Fertility goals
• Overall health and inflammatory burden

At Atlas, we recognise that adenomyosis doesn’t exist in isolation.

Hormone balance, iron status, inflammation, thyroid function, and metabolic health all play a role in symptom expression and resilience.

FAQS

What is the difference between adenomyosis and endometriosis?

• Adenomyosis occurs within the muscle wall of the uterus, whereas endometriosis involves similar tissue growing outside the uterus.

Can adenomyosis cause heavy periods?

• Yes, heavy and prolonged menstrual bleeding is one of the most common symptoms.

Is adenomyosis inflammatory?

• Yes, adenomyosis involves chronic inflammation within the uterine tissue, contributing to pain and symptoms.

Final Thoughts

Adenomyosis is a real, life-affecting condition – but it’s still too often overlooked or normalised.

If you’re experiencing heavy bleeding, severe cramps, persistent pelvic pain, or unexplained fatigue, your symptoms deserve investigation.

With the right insight and support, many people are able to reduce symptoms, protect fertility, and regain quality of life.

Understanding what’s happening beneath the surface is the first step toward meaningful change.