Endometriosis and adenomyosis are different conditions, but they can have overlapping symptoms. Some people have one. Some people have both.
Understanding the difference can help you ask clearer questions in appointments and make better sense of scan reports, treatment discussions or surgery notes.
What is endometriosis?
Endometriosis is a chronic inflammatory condition where tissue similar to the lining of the uterus is found outside the uterus.
This tissue can form lesions and may cause inflammation, scar tissue, adhesions, cysts called endometriomas, pain, organ symptoms and fertility difficulties for some people.
Endometriosis may involve areas such as:
- ovaries
- fallopian tubes
- outside of the uterus
- pelvic lining
- bowel
- bladder
- ureters
- diaphragm
- lungs or chest cavity
- abdominal wall
- surgical scars
- nerves or nearby tissues
- other extra-pelvic sites
Endometriosis is not simply a uterine condition. It can affect different parts of the body.
What is adenomyosis?
Adenomyosis is a condition where tissue similar to the lining of the uterus is found within the muscular wall of the uterus.
The uterus has a muscle layer called the myometrium. In adenomyosis, endometrial-like tissue grows into this muscle wall. This can make the uterus enlarged, tender or painful for some people.
Adenomyosis is a condition of the uterus itself.
The simple difference
The simplest way to understand the difference is:
Endometriosis: endometrial-like tissue is found outside the uterus.
Adenomyosis: endometrial-like tissue is found within the muscle wall of the uterus.
They are different conditions, but they can exist together.
Symptoms of endometriosis
Endometriosis symptoms can vary depending on where the disease is and how the body responds.
Symptoms may include:
- painful periods
- pelvic pain
- pain outside periods
- pain during or after sex
- bowel symptoms
- bladder symptoms
- back, hip, groin or leg pain
- fatigue
- nausea
- fertility difficulties
- pain around ovulation
- symptoms outside the pelvis in some cases
Symptoms may be cyclical, constant or unpredictable.
Symptoms of adenomyosis
Adenomyosis is often linked with symptoms involving the uterus.
Symptoms may include:
- heavy periods
- painful periods
- pelvic pain
- a feeling of pressure or heaviness
- bloating or an enlarged-feeling uterus
- pain during sex
- bleeding that lasts longer than expected
- anaemia or low iron from heavy bleeding
- fatigue related to heavy bleeding
- fertility or pregnancy-related concerns for some people
Not everyone with adenomyosis has symptoms. Some people only find out after imaging or after a hysterectomy specimen is examined.
Why they can be confused
Endometriosis and adenomyosis can both cause:
- painful periods
- pelvic pain
- heavy bleeding
- pain during sex
- fertility concerns
- fatigue
- symptoms that affect daily life
Because symptoms overlap, it may be difficult to tell the difference based on symptoms alone.
A person may be treated for suspected endometriosis when adenomyosis is also present, or adenomyosis may be missed if the focus is only on endometriosis.
This is why good assessment matters.
Can you have both?
Yes.
Some people have both endometriosis and adenomyosis. When both are present, symptoms can be more complex.
For example, endometriosis may contribute to bowel, bladder, nerve or extra-pelvic symptoms, while adenomyosis may contribute to heavy bleeding, uterine cramping, pressure or an enlarged uterus.
If symptoms do not improve as expected after treatment, it may be worth asking whether another condition, such as adenomyosis, could also be contributing.
How are they diagnosed?
Diagnosis depends on symptoms, medical history, examination where appropriate, imaging and sometimes surgery or pathology.
Endometriosis may be assessed through:
- symptom history
- pelvic examination, where appropriate
- specialist ultrasound
- MRI
- referral to gynaecology or an endometriosis specialist
- laparoscopy in some cases
- histology if tissue is removed
Adenomyosis may be assessed through:
- symptom history
- pelvic examination, where appropriate
- ultrasound
- MRI
- specialist gynaecology review
Adenomyosis can sometimes be suspected on imaging, but diagnosis may not always be straightforward.
Can scans show endometriosis or adenomyosis?
Specialist ultrasound and MRI can sometimes identify signs of endometriosis or adenomyosis.
Endometriomas, deep endometriosis and adenomyosis may be more visible than superficial endometriosis.
A normal scan does not always rule out endometriosis. It also does not always explain symptoms fully.
If symptoms continue, ask what else should be considered and whether specialist imaging or referral is appropriate.
How treatment can differ
Treatment depends on the person, symptoms, severity, fertility goals, age, previous treatment, other conditions and preferences.
Endometriosis treatment may include:
- pain relief
- hormonal treatment for symptom control
- pelvic physiotherapy
- pain management support
- fertility care
- excision surgery in some cases
- multidisciplinary care if bowel, bladder, thoracic, nerve or other organ involvement is suspected
Adenomyosis treatment may include:
- pain relief
- hormonal treatment
- medicines to reduce bleeding
- intrauterine system options for some people
- fertility support where needed
- procedures or surgery in selected cases
- hysterectomy in some cases when fertility is not desired and other options have not helped
No treatment should be presented as right for everyone. Decisions should be made with a healthcare professional who can explain benefits, risks and alternatives.
Hysterectomy: why the distinction matters
A hysterectomy removes the uterus.
Because adenomyosis is within the uterus, hysterectomy may be discussed as a definitive treatment for adenomyosis when someone does not want future pregnancies and other treatments have not helped.
Endometriosis is different because it is found outside the uterus. A hysterectomy does not automatically treat endometriosis lesions elsewhere in the body.
This is why it is important to know whether symptoms may be coming from endometriosis, adenomyosis, or both.
Questions to ask your healthcare professional
You may want to ask:
- Could my symptoms suggest endometriosis, adenomyosis, or both?
- Could adenomyosis explain heavy bleeding or uterine pain?
- Could endometriosis explain bowel, bladder, nerve or pain outside periods?
- Would specialist ultrasound or MRI help?
- Are there signs of endometriomas or deep endometriosis?
- Are there signs of adenomyosis?
- What treatment options match my symptoms and goals?
- How could treatment affect fertility?
- If surgery is being discussed, what exactly would be treated?
- If hysterectomy is mentioned, how would possible endometriosis outside the uterus be assessed?
- Should I be referred to an endometriosis specialist or multidisciplinary team?
When to seek medical advice
Speak with a healthcare professional if you have:
- painful periods that affect daily life
- heavy bleeding
- bleeding between periods
- pelvic pain
- pain during or after sex
- bowel or bladder symptoms
- fatigue linked with heavy bleeding or pain
- difficulty getting pregnant
- symptoms that are worsening
- symptoms that continue despite treatment
Seek urgent medical help if you have severe sudden pain, fainting, fever, heavy bleeding that feels unsafe, chest pain, shortness of breath, or new bladder or bowel control problems.
Final reminder
Endometriosis and adenomyosis are different conditions, but they can overlap.
Endometriosis is found outside the uterus. Adenomyosis is found within the muscle wall of the uterus.
Both can cause real pain and disruption. Both deserve proper assessment.
Understanding the difference can help you ask better questions, prepare for appointments and make sense of your care options.
Use our Prepare for Appointment Tool to organise your symptoms, bleeding pattern, pain pattern and questions before speaking with a healthcare professional.