Adenomyosis and endometriosis are menstrual (period) conditions that can affect women and people assigned female at birth (AFAB). While the two conditions are similar, there are important differences in how they affect your body and how they show up as symptoms. An ultrasound scan can help a clinician identify whether you have adenomyosis or endometriosis, ensuring you get the right treatment.

We’ll guide you through the differences between adenomyosis vs endometriosis, their symptoms, and how adenomyosis can affect fertility and pregnancy. We’ll also talk you through the different scans that can help diagnose adenomyosis or endometriosis.

What is adenomyosis?

Adenomyosis (uterine adenomyosis) is when endometrial tissue grows deep into the muscle layer of the uterus (womb). It affects anyone with periods but often affects people between the ages of 30 and 50. Experts used to think adenomyosis and endometriosis were pretty much the same thing, just in different places. In fact, experts used to call adenomyosis ‘endometriosis interna’ But now we know that they’re different. They show up in different places, and they have some different symptoms and complications.

What is the difference between endometriosis and adenomyosis?

Adenomyosis and endometriosis are both conditions in which endometrial tissue, similar to the lining of the womb, grows somewhere it shouldn’t normally grow. While it’s possible to have both at the same time, they're not the same condition. Understanding the differences between adenomyosis vs endometriosis can help you get the right scan and treatment.

Endometriosis is when this tissue grows somewhere else in the body, often the ovaries, fallopian tubes and pelvic cavities and into the ligaments surrounding the womb.

Both conditions have symptoms that can be hard to bear and life-changing for many people, but it’s important to know that each can be managed and improved with the right treatment.

Adenomyosis affects anyone with periods but often affects people between the ages of 30 and 50. Endometriosis can affect people of any age who have periods, including teenagers

What are the symptoms of adenomyosis?

While some people have no signs of the condition, symptoms of adenomyosis can include:

heavy, painful periods
pain during sex
abnormal bleeding
chronic pelvic pain
bloating or a heavy, full feeling in your tummy
trouble conceiving
an enlarged womb

Adenomyosis pain can be mild, moderate or severe, and vary in when and for how long it lasts.

How symptoms differ between adenomyosis vs endometriosis

Many symptoms of endometriosis are similar to adenomyosis, such as pelvic pain, heavy painful periods, pain during sex and trouble conceiving. However, people with endometriosis may also have:

pain when you poo or wee
abdominal pain
back pain
tiredness
constipation or diarrhoea
feeling sick

Adenomyosis vs endometriosis which is worse?

This is hard to answer, as both can affect your quality of life, and both have successive stages of severity. Research shows that people with adenomyosis might have a higher chance of getting certain types of cancer, like endometrial and thyroid cancers, while those with endometriosis might have a higher risk of other cancers, like ovarian cancers.

Both adenomyosis and endometriosis can make it harder to get pregnant, but they do it in their own ways. Endometriosis can lead to infertility due to the distortion of pelvic anatomy, inflammation, and the formation of adhesions that can affect your reproductive organs. Adenomyosis, although also associated with infertility, may not have the same level of impact as endometriosis.

What are the different adenomyosis stages?

Diagnosing adenomyosis into four stages helps doctors make decisions about treatment and predict how the condition might develop. However, experts agree we need more research to decide how to stage adenomyosis so everyone gets the best care possible. For now, the condition is staged like this:

Stage 1: Early adenomyosis

Symptoms are often mild or absent, making early uterine adenomyosis tricky to detect. However, some endometrial tissue will grow into the womb's wall. But it's crucial not to ignore any unusual pain or discomfort. Seeing a clinician promptly and having a scan can make a big difference in how the disease progresses at this stage.

Stage 2: Moderate adenomyosis

As the condition develops, the tissue infiltration will be more noticeable on a scan, affecting more of the uterine wall. You might notice heavier, more painful periods and experience bloating and pain during sex. Seeking advice if you notice any of these symptoms is a good idea.

Stage 3: Severe adenomyosis

In stage three, adenomyosis can start to change the shape of the uterus. Symptoms can worsen, causing significant pain that can interfere with everyday activities. Heavy, painful periods may get worse. It’s vital to get advice and treatment at this stage.

Stage 4: Advanced adenomyosis

Adenomyosis stage 4 involves extensive tissue infiltration into the wall of the womb and potential damage to the uterus. Symptoms are often severe and chronic, including persistent pelvic pain, heavy bleeding, and painful sex. It’s really important to get a diagnosis and a personal treatment plan for the condition at this stage.

What is the process for adenomyosis diagnosis?

Most people need to have a series of appointments and tests to be diagnosed with adenomyosis. Usually, the first appointment is with a GP or doctor to talk about your symptoms and your medical history. You may need to have a physical examination, including a pelvic exam, so that your doctor can check for any abnormalities. They may also feel your tummy to check for bloating or swelling.

The next step is usually an ultrasound scan that allows your clinician to check for abnormalities inside the womb and surrounding tissues. This can help them differentiate between adenomyosis and endometriosis. You may be offered a transvaginal ultrasound scan, a quick internal procedure with a slender probe) or a transabdominal ultrasound scan (external ultrasound).

If the results of an ultrasound scan are inconclusive, your clinician may suggest having an MRI scan, which can show clearer images of the womb and help to differentiate between adenomyosis and endometriosis more clearly.

Sometimes, looking at endometrial tissue under a microscope is the best way to diagnose adenomyosis, and this would require having a biopsy. However, most people get their diagnosis from ultrasound or MRI.

What do adenomyosis ultrasound images look like?

The images from an adenomyosis ultrasound vs normal ultrasound may show signs of the condition, although these can be subtle. There may be a thickening of the uterine wall, the womb itself may appear uneven or irregular around the edges, and there may be darker spots that suggest masses of tissue. Parts of the uterine wall tissue may look mottled or speckled, showing that the tissue is different, which is often a sign of adenomyosis on ultrasound.

Your clinician may also let you know if you have focal or diffuse adenomyosis. Focal adenomyosis means the tissue is concentrated in specific uterine spots. Diffuse adenomyosis means the tissue is spread throughout larger areas of the womb.

Adenomyosis and pregnancy

Unfortunately, there is a higher risk of complications during pregnancy if you have adenomyosis. Research into thousands of pregnant patients with the condition as recently as 2023 found an increased risk of:

miscarriage (52.9% increased risk)
premature delivery (42%)
smaller babies (intrauterine growth restriction) (25%)
high blood pressure: (17.7%)
placental abruption (198%)
caesarean (9.9%)

Research has found that people with diffuse adenomyosis have a higher risk of miscarriage, pre-eclampsia, and giving birth prematurely compared to people with the focal type. This might be because diffuse adenomyosis interferes more with how the placenta forms, but we don’t know for sure.

Adenomyosis and fertility: Should I be concerned?

While it’s not clear if adenomyosis directly affects fertility, experts think it could have a negative impact because of symptoms like abnormal bleeding. It can also cause inflammation and changes to your womb which may affect the chances of an embryo attaching and growing as expected.

If you're concerned about adenomyosis and its potential effects on your fertility, it's a good idea to talk to a clinician who specialises in adenomyosis fertility and reproductive health.

Does adenomyosis cause pain when not menstruating?

Yes, it can. You may experience pelvic pain, pain during sex and even chronic pain due to inflammation. This can affect your everyday activities and quality of life, so it’s important to take the next steps to getting diagnosed and having treatment.

What are the next steps?

If you think you may have endometriosis or adenomyosis, see your GP or a clinician to talk about your symptoms and medical history. You can wait to be referred for an NHS scan or book a transvaginal or pelvic ultrasound for adenomyosis or endometriosis diagnosis within days using Scan.com. You can book an appointment for a phone consultation with our clinicians before going ahead. If you decide a scan is right for you, the consultation cost will be deducted from your scanning fee. There's nothing to lose, and our clinicians can help you feel confident in your choice.

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Endometriosis vs. Adenomyosis: Understanding the Difference (N.D.) https://www.centerofendometriosis.com/blog/endometriosis-vs-adenomyosis-understanding-the-difference

Endometriosis. (2022). https://www.nhs.uk/conditions/endometriosis/

Guo, S. (2020). The Pathogenesis of Adenomyosis vis-à-vis Endometriosis. https://www.mdpi.com/2077-0383/9/2/485

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Van den Bosch, T. and Van Schoubroeck, D. (2018). Ultrasound diagnosis of endometriosis and adenomyosis: State of the art. https://www.sciencedirect.com/science/article/abs/pii/S1521693418300312?via%3Dihub

What is the difference between adenomyosis and endometriosis? (2023). https://www.medicalnewstoday.com/articles/adenomyosis-vs-endometriosis

Adenomyosis vs Endometriosis: Symptoms, Similarities, and When To Get an Adenomyosis Ultrasound