Adenomyosis vs Endometriosis: What's the Difference?

Adenomyosis and endometriosis share similar symptoms, from painful periods and pelvic pain to heavy bleeding and bloating. That overlap can make it hard to understand what your symptoms really mean. The main difference is the location. Adenomyosis affects the muscular wall of the womb (uterus), while endometriosis occurs outside of the uterus.

Both are long-term reproductive health conditions that are often overlooked or confused with other problems. Plus, they don’t always cause the same symptoms, require the same diagnostic tests or respond to the same treatment, so getting a diagnosis can be challenging. 

This guide explains those differences in more detail without asking you to become a gynaecology expert first.  

Adenomyosis and Endometriosis at a Glance

Adenomyosis and endometriosis are similar but separate chronic reproductive health conditions. Both involve tissue similar to the endometrium growing in areas of the body where it shouldn’t, but the main distinction is where this tissue is found. 

What is Adenomyosis?

Adenomyosis is a condition in which tissue similar to the womb lining grows into the womb muscles, making the lining thicker and causing the uterus to enlarge or become tender.* Because adenomyosis is confined to the uterus, its symptoms often centre on painful, heavy or prolonged periods. You may experience pelvic pressure or pain throughout the month, while others may have no symptoms. 

It was previously thought that adenomyosis affected people in their 30s and 40s who had given birth, but this is not the case. Although having children is a risk factor, adenomyosis can affect younger people and those who have never given birth.** So don’t let your age and your pregnancy history rule it out when looking for a diagnosis for your symptoms.

*Consoli RJ, et al. (2026). Adenomyosis.

**NHS. (2023). Adenomyosis.

What is Endometriosis?

Endometriosis occurs when tissue similar to the uterine lining grows elsewhere in the body, so unlike adenomyosis, it is not confined to the womb.* 

It commonly affects:

• The ovaries, fallopian tubes and pelvic lining

• The bowel or bladder

• In some rare cases, areas outside the pelvis like the diaphragm or brain 

As the tissue grows in unfamiliar areas, endometriosis can cause inflammation, scar tissue, cyst-like growths on the ovaries and adhesions (thick scar tissue that causes pelvic organs to stick together). Symptoms can begin as early as your first period or during adolescence, but it can take, on average, 9 years and 4 months to get a diagnosis.**

*NHS. (2024). Endometriosis.

**Endometriosis UK. (2026). Endometriosis UK release new report highlighting alarming increase in endometriosis diagnosis times. 

Comparing the Symptoms of Adenomyosis and Endometriosis

Adenomyosis and endometriosis share similar symptoms, which can make distinguishing between the two challenging. Both can cause debilitating period pain, constant pelvic pain, painful sex and fertility problems. Some people have few or no noticeable symptoms. However, certain patterns can help your clinician decide which investigations are most appropriate.

Adenomyosis pain is often described as central cramping that may be accompanied by a heavy feeling in the pelvis, whereas endometriosis pain can be more widespread, affecting the lower back, bowel or bladder.

The National Institute for Health and Care Excellence (NICE) advises clinicians to remember that pain accompanying heavy menstrual bleeding can be caused by endometriosis rather than adenomyosis.* In other words, heavy bleeding does not automatically mean adenomyosis, especially if you also have bowel pain, bladder pain, or pain during sex.

*NICE. (2026). Heavy menstrual bleeding: assessment and management.  

How Is Each Condition Diagnosed?

For either condition, diagnosis usually begins with a detailed conversation with your clinician about: 

• Your periods, pain and bleeding patterns

• Your bowel and bladder symptoms

• Pain during or after sex

• Any difficulties becoming pregnant 

Keeping a symptoms diary for 2 or 3 menstrual cycles may help you identify patterns more easily. 

You should then be offered imaging scans or a type of keyhole surgery, depending on your condition, to confirm the diagnosis. 

Diagnosing adenomyosis

If you think that you have adenomyosis, your clinician may recommend a transvaginal ultrasound as the preferred first-line imaging test.* This involves placing a thin ultrasound probe inside your vagina to get detailed images of your uterus.

The scan can help show: 

• Thickening of the uterine muscle

• Small cysts within it

• Changes to the boundary between the uterine lining and muscle

If your ultrasound results are unclear or you need more detail, you may be offered an MRI, but this is usually not the first test you’ll be offered. That’s because a transvaginal ultrasound is more accurate than an abdominal ultrasound or MRI for detecting adenomyosis.

Historically, adenomyosis could only be confirmed by examining the uterus after a hysterectomy. Tissue examination remains the most certain confirmation, but modern imaging means many people can now receive a diagnosis without invasive surgery.

*NICE. (2024). Endometriosis: diagnosis and management.

Diagnosing endometriosis

If your clinician suspects that you may have endometriosis, you should be offered a transvaginal ultrasound, even if an abdominal or pelvic examination is normal.* A normal transvaginal ultrasound scan also does not rule out endometriosis, particularly superficial disease that may be difficult to see.

Specialist ultrasound or MRI can help identify deep endometriosis and assess whether the bowel or bladder may also be affected. If your scan and test results are normal, a laparoscopy, a type of keyhole surgery used to examine the pelvis and potentially take a biopsy or treat visible disease, is also an important diagnostic option. 

*NICE. (2024). Endometriosis: diagnosis and management.

Can You Have Both Endometriosis and Adenomyosis?

Yes. Having one condition does not stop you from having the other, and the two are frequently found together. Although this is quite a broad finding, recent research has shown that between 30 and 90% of people with endometriosis also have adenomyosis.* Similarly, 60 to 80% of people with adenomyosis are also living with endometriosis.*

Those figures should not be read as one universal risk. People undergoing fertility treatment or gynaecological surgery are different from the general population, and scan criteria have not always been consistent. The useful takeaway is simpler – the overlap is substantial enough that persistent symptoms may justify investigating both conditions.

Yet, having both can complicate diagnosis because treating one source of pain or bleeding may not resolve the symptoms caused by the other. For example, a hysterectomy would remove adenomyosis but will not remove endometriosis affecting areas outside the uterus.

*Koroneos Z, et al. (2026). Comorbidity of endometriosis and adenomyosis: A systematic review examining the impact of co-morbid disease on fertility and pregnancy outcomes. 

Is Treatment for Adenomyosis and Endometriosis Different?

Yes. Although there is an overlap in the treatments available to manage the symptoms of adenomyosis and endometriosis, such as pain, the long-term options are not the same. Your symptoms, whether you want to become pregnant, previous treatments, and the location of the condition can all affect which treatment is most appropriate for you. 

Adenomyosis Treatment

Treatments for adenomyosis include:

• Non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen for pain management and inflammation

• Tranexamic acid to reduce heavy menstrual bleeding

• Hormonal treatments, including the combined contraceptive pill, progestogen-only pill (mini pill), or the intrauterine system (IUS), known as the hormonal coil, to help make your periods lighter and less painful

• Surgical treatments, such as a hysterectomy, to remove your womb may be appropriate if your symptoms are severe and you are not looking to become pregnant – this is the only cure available for adenomyosis

Endometriosis Treatment

Endometriosis treatments include:

• Painkillers, such as paracetamol or NSAIDs like ibuprofen, can be given to relieve pain

• Hormonal contraception or other hormone-based treatments, such as the combined pill, to help balance your hormone levels, reducing pain and menstrual activity – not suitable if you want to become pregnant

• Surgery to remove areas of endometriosis or ovarian cysts, parts of the bladder or bowel, or your womb if affected

• Fertility advice or treatment when you want to get pregnant

Although a hysterectomy may be recommended if endometriosis is affecting your womb, it will not cure the condition if it is affecting other areas of the body.* This should be discussed with your clinician before making a decision about your treatment. 

*NICE. (2024). Endometriosis: diagnosis and management.

FAQs

Is adenomyosis a type of endometriosis?

No. Adenomyosis is not a type of endometriosis, but they are closely related and cause similar side effects. Adenomyosis affects the muscle of the uterus, while endometriosis can develop outside of the womb. You can also have both conditions at once, but one is not a form or stage of the other.

Does hysterectomy cure endometriosis?

No. Endometriosis grows outside the womb (on the ovaries, bowel, bladder or pelvic lining), so removing the womb during a hysterectomy doesn’t remove the disease growing elsewhere.*

*NICE. (2024). Endometriosis: diagnosis and management. NICE guideline NG73.

Which is more painful, adenomyosis or endometriosis?

Neither adenomyosis nor endometriosis is automatically more painful than the other because pain severity can differ from person to person. Adenomyosis is often associated with intense central cramping and heavy periods, while endometriosis can cause more widespread pelvic, bowel, bladder pain or pain during sex. If you are experiencing pain, especially if it is severe or disrupting your daily life, speak to your GP for further advice. 

Can adenomyosis and endometriosis both affect fertility?

Yes. Endometriosis is strongly linked with difficulties getting pregnant. While adenomyosis can reduce fertility, it is also associated with pregnancy complications, such as implantation issues and an increased risk of miscarriage. However, it is still possible to become pregnant with either condition, but you may need specialist advice and treatment.