What Is Adenomyosis, and How Is It Different from Endometriosis?

Adenomyosis is a lesser-known but often debilitating condition that affects the uterus, most commonly in women over 30. Like endometriosis, it involves tissue similar to the womb lining growing where it shouldn’t, but in this case, it grows into the muscle wall of the uterus.

This key difference makes diagnosis challenging and delays common. So what exactly is adenomyosis, how can you recognise it, and how is it managed? Here's what you need to know.

What Is Adenomyosis?

Adenomyosis occurs when the tissue that normally lines the womb

starts growing into the muscle wall of the uterus. This misplaced tissue continues to act as it would during a typical menstrual cycle, thickening, breaking down, and bleeding. The result? An enlarged uterus, painful periods, and in some cases, chronic pelvic pain.

While it can affect anyone who menstruates, it’s most commonly diagnosed in people over the age of 30 and often resolves after menopause.

Key Symptoms to Watch For

Adenomyosis symptoms can vary widely, some people experience no symptoms at all, while others have pain and bleeding severe enough to impact daily life.

Period-related symptoms:

• Painful periods that may be intense or cramp-like

• Heavy or prolonged menstrual bleeding

  
  

Other possible signs:

• Chronic pelvic pain

• Bloating or a feeling of fullness in the lower abdomen

• Pain during sex

• A tender or enlarged uterus (though this might only be detected during a physical exam)

  
  

If you’re experiencing any of these symptoms, especially if they interfere with work, relationships, or everyday tasks, it’s worth speaking to your GP.

Adenomyosis vs. Endometriosis: What’s the Difference?

It’s easy to confuse adenomyosis with endometriosis. Both involve tissue similar to the womb lining growing where it shouldn’t, and some people live with both conditions. But medically, they are distinct.

In adenomyosis, the tissue grows into the muscular wall of the uterus itself, often causing the uterus to become enlarged or tender. In contrast, endometriosis involves this tissue growing outside the uterus, typically on the ovaries, fallopian tubes, or the lining of the pelvis.

While both can cause pelvic pain and heavy periods, endometriosis is more likely to trigger pain in other parts of the body and at different times throughout the menstrual cycle, not just during bleeding. The overlapping symptoms can make it difficult to distinguish between the two, and a clear diagnosis may require imaging or, in some cases, surgery.

What Causes Adenomyosis?

The exact cause remains unknown. Some theories suggest it may be related to:

• Invasive procedures such as C-sections or uterine surgery

• Inflammation of the uterine lining

• Hormonal imbalances

  
  

Although the condition often improves after menopause, its impact during the reproductive years can be significant.

How Is It Diagnosed?

Diagnosis can be difficult, especially because adenomyosis symptoms overlap with other gynaecological conditions. Your doctor may use:

• Pelvic exams to check for uterine enlargement

• Ultrasound or MRI scans to look for signs of tissue growth

• In rare cases, biopsies or surgical procedures may be required for confirmation

  
  

Treatment Options

Not everyone with adenomyosis needs treatment. If symptoms are mild, you may simply be monitored over time. For those with more severe pain or bleeding, options include:

• Hormonal treatments, such as contraceptive pills, IUDs, or GnRH analogues to regulate the menstrual cycle and reduce symptoms

• Anti-inflammatory medication, like ibuprofen, to manage pain

• Hysterectomy, or removal of the uterus, which is the only definitive cure

  
  

Treatment plans are highly individual and depend on your symptoms, age, and whether you plan to have children.

Why Awareness Matters

Adenomyosis can be debilitating, yet many people go years without a proper diagnosis, either because symptoms are dismissed or mistaken for other conditions. Increasing awareness of adenomyosis can help more people seek help earlier and push for better diagnostic tools and treatments.

If you suspect you might have adenomyosis, don’t suffer in silence. Talk to your GP, track your symptoms, and advocate for yourself. No one should have to live with pain that remains undiagnosed or misunderstood.