Fibroids vs Endometriosis: Symptoms, Differences and Diagnosis

Fibroids vs Endometriosis: Symptoms, Differences and Diagnosis

Pelvic pain, heavy periods and menstrual cramps are common concerns for many women. However, when these symptoms become severe, persistent or start interfering with everyday life, they may indicate an underlying gynaecological condition.

Two conditions that can cause overlapping symptoms are uterine fibroids and endometriosis. Although both can affect menstrual health and, in some cases, fertility, they are different conditions that develop in different ways.

Understanding the difference between fibroids and endometriosis can help you recognise possible symptoms, know what to discuss with your gynaecologist and explore appropriate treatment options.

In this guide, we explain what fibroids and endometriosis are, how their symptoms differ, how they are diagnosed and when medical advice may be necessary.

What Are Uterine Fibroids?

Uterine fibroids are non-cancerous growths that develop from the muscle tissue of the uterus. They are also known as leiomyomas or myomas.

Fibroids vary in number, size and location. Some women have a single small fibroid, while others may have multiple growths. Their symptoms depend partly on their size and where they develop.

Fibroids are commonly classified according to their location:

• Intramural fibroids: Develop within the muscular wall of the uterus.
• Submucosal fibroids: Grow towards the inner cavity of the uterus and may contribute to heavy menstrual bleeding.
• Subserosal fibroids: Grow towards the outer surface of the uterus and may cause pressure symptoms when sufficiently large.

Some women with fibroids experience heavy menstrual bleeding, pelvic discomfort or frequent urination. Others have no noticeable symptoms, and fibroids are discovered during a routine examination or ultrasound.

Fibroids are not cancer, and having them does not automatically mean treatment is necessary. Management depends on symptoms, fibroid characteristics, reproductive plans and overall health. Source: ACOG

What Is Endometriosis?

Endometriosis is a chronic condition in which tissue similar to the lining of the uterus grows outside the uterus. It most commonly affects areas within the pelvis, including the ovaries, fallopian tubes and tissues around the uterus. In some cases, it can involve the bowel or bladder.

This tissue responds to hormonal changes during the menstrual cycle and can contribute to inflammation, pain and scar tissue formation, known as adhesions.

Common symptoms include:

• Severe period pain that affects daily activities.
• Persistent or recurring pelvic pain.
• Pain during or after sexual intercourse.
• Pain during bowel movements or urination, particularly around menstruation.
• Fatigue.
• Difficulty becoming pregnant in some cases.

The severity of symptoms does not always reflect the extent of endometriosis. Some women experience significant pain with limited visible disease, while others may have few symptoms despite more extensive involvement.

Endometriosis is a long-term condition, but treatments are available to help manage symptoms and support quality of life. Source: NHS

Fibroids vs Endometriosis: What Is the Difference?

Although fibroids and endometriosis can both cause pelvic pain and menstrual problems, their underlying characteristics are different.

The key distinction is that fibroids are growths arising from the muscular tissue of the uterus, whereas endometriosis involves tissue similar to the uterine lining growing outside the uterus.

Here is how the two conditions compare.

1. Location and nature of the condition

Fibroids develop in or around the uterus. Their effects often depend on their size and position.

Endometriosis involves tissue outside the uterus, such as around the ovaries, fallopian tubes or pelvic lining. The resulting inflammation and adhesions can affect nearby organs.

2. Menstrual symptoms

Fibroids, particularly those that affect the uterine cavity, may cause heavy or prolonged periods and sometimes bleeding between periods.

Endometriosis is often associated with painful periods, recurring pelvic pain and pain that may begin before menstruation. Some women with endometriosis also experience heavy bleeding.

Because these symptoms overlap, menstrual changes alone cannot reliably distinguish between the two conditions.

3. Type of pain

Fibroid-related discomfort may feel like pelvic heaviness, pressure or a dull ache. Larger fibroids can sometimes cause back discomfort, constipation or frequent urination.

Endometriosis more commonly causes period-related pelvic pain, pain during sex or pain with bowel movements or urination. However, symptoms vary, and either condition can cause substantial discomfort.

4. Effect on fertility

Both conditions may affect fertility in some women, but the effects differ.

Fibroids may interfere with conception or pregnancy depending on their size and location, particularly when they distort the uterine cavity.

Endometriosis may affect fertility through inflammation, adhesions, ovarian involvement or changes affecting the reproductive organs.

Neither diagnosis automatically means that a woman will experience infertility. Many women with either condition conceive naturally, and fertility care can be discussed when needed.

5. Diagnosis

Ultrasound is commonly used to identify uterine fibroids and assess their size and location.

Endometriosis can be more challenging to identify. Doctors may consider symptoms, examination findings and imaging such as ultrasound or MRI. A normal scan does not exclude all forms of endometriosis.

The diagnostic approach depends on the person's symptoms, clinical history and the findings of initial investigations.

Symptoms of Fibroids vs Endometriosis

Recognising symptom patterns can help you decide when to seek an assessment. However, symptoms are clues rather than a definitive diagnosis.

Symptoms more commonly associated with fibroids

Fibroids may cause:

• Heavy menstrual bleeding or periods lasting longer than usual.
• Menstrual cramps or pelvic discomfort.
• A feeling of fullness or pressure in the lower abdomen.
• Frequent urination when a fibroid presses on the bladder.
• Constipation or difficulty passing stools when nearby structures are affected.
• Lower back discomfort.
• Anaemia related to prolonged or heavy blood loss.

Some fibroids cause no symptoms and require only monitoring.

Symptoms more commonly associated with endometriosis

Endometriosis may cause:

• Severe period pain that disrupts everyday activities.
• Pelvic pain before, during or sometimes outside menstruation.
• Pain during or after sex.
• Painful bowel movements, especially around periods.
• Pain during urination, particularly when symptoms are cyclical.
• Fatigue and reduced quality of life.
• Difficulty becoming pregnant in some women.

Not everyone experiences all these symptoms. Some women have endometriosis without obvious symptoms and discover it during an evaluation for fertility concerns or another medical reason.

Can you have both conditions?

Yes. Fibroids and endometriosis can occur in the same person. Having symptoms that seem consistent with one condition does not exclude the other.

If symptoms persist despite treatment or do not fit an initial diagnosis, your gynaecologist may recommend further assessment.

What Causes Fibroids and Endometriosis?

The exact causes of both conditions are not fully understood. However, researchers have identified factors that may contribute to their development.

Possible factors associated with fibroids

Fibroid development and growth are influenced by several factors, including hormonal influences and genetic susceptibility.

Factors associated with a higher likelihood of fibroids include:

• A family history of fibroids.
• Reproductive age.
• Individual hormonal and biological factors.

The presence of these factors does not mean that fibroids will definitely develop. Fibroids also vary considerably in how they grow over time.

Possible factors associated with endometriosis

The exact mechanism behind endometriosis remains uncertain. Several biological processes may contribute, including hormonal influences, inflammation, immune-system factors and genetic susceptibility.

Having a close family member with endometriosis may increase the likelihood of developing the condition.

Endometriosis is not caused by poor hygiene, and experiencing period pain does not mean someone has done anything wrong.

How Are Fibroids and Endometriosis Diagnosed?

A gynaecologist will usually begin by understanding your symptoms, menstrual history, medical background and reproductive goals. You may be asked about the timing of pain, bleeding patterns, bowel or bladder symptoms and whether the symptoms interfere with daily activities.

Depending on the findings, one or more of the following assessments may be recommended.

1. Pelvic examination

A pelvic examination may help identify uterine enlargement, tenderness or other findings that require further investigation.

However, a normal examination does not rule out fibroids or endometriosis.

2. Ultrasound

Pelvic ultrasound is commonly used to assess fibroids, including their size, number and location. It can also identify certain features associated with endometriosis, such as ovarian endometriomas.

A transvaginal ultrasound may provide more detailed images when appropriate and acceptable to the patient.

However, ultrasound cannot detect every type of endometriosis, particularly some superficial lesions.

3. MRI

Magnetic resonance imaging (MRI) may be recommended when more detailed information about pelvic structures is needed. It can help assess certain types of endometriosis and clarify the size, location or characteristics of fibroids in selected cases.

MRI is not necessary for everyone.

4. Hysteroscopy or other uterine investigations

If fibroids affecting the uterine cavity are suspected, a doctor may recommend hysteroscopy or another investigation to examine the inside of the uterus more closely.

The choice depends on the suspected location of the fibroid and the clinical question being investigated.

5. Laparoscopy for endometriosis

Laparoscopy is a surgical procedure in which a small camera is inserted through an incision in the abdomen to examine the pelvic organs. It may be considered when symptoms, imaging and treatment response warrant further evaluation.

Importantly, surgery is not always required before endometriosis can be suspected, diagnosed clinically or treated. Current guidance supports using symptoms, clinical assessment and imaging to guide care, with laparoscopy considered in appropriate circumstances.

Your doctor will discuss the benefits, limitations and risks of any proposed procedure. Source: ACOG clinical guidance

Treatment Options for Fibroids vs Endometriosis

Treatment depends on the condition, the severity of symptoms, age, medical history and whether you wish to become pregnant in the future.

Not everyone needs medication or surgery. If symptoms are mild and there are no concerning findings, monitoring may be appropriate.

Treatment options for fibroids

Monitoring: Fibroids that are not causing symptoms or complications may be monitored through follow-up appointments and imaging when indicated.

Medicines: Depending on the situation, medicines may help manage heavy menstrual bleeding or pain. Some hormonal treatments can reduce bleeding, while certain specialist medicines may temporarily shrink fibroids.

Procedures: Selected fibroids may be treated using procedures such as uterine artery embolisation or other minimally invasive techniques. Suitability depends on the type of fibroid and reproductive plans.

Surgery: A myomectomy removes fibroids while preserving the uterus. A hysterectomy removes the uterus and permanently ends the ability to carry a pregnancy. Other surgical approaches may be appropriate in selected cases.

Your gynaecologist can explain which options are suitable, including how they may affect future pregnancy.

Treatment options for endometriosis

Pain relief: Appropriate pain-relieving medicines may help manage symptoms. Your doctor can advise which medicines are suitable for your health circumstances.

Hormonal treatment: Hormonal medicines may reduce menstrual activity and help manage endometriosis-related pain. Some options are contraceptive, so treatment choices should take your pregnancy plans into account.

Surgery: Laparoscopic surgery may be considered to remove or treat endometriosis lesions, adhesions or certain ovarian cysts when indicated. Surgery has potential risks, and symptoms may return.

Fertility support: If endometriosis is affecting conception, a gynaecologist or fertility specialist can discuss options based on age, ovarian reserve, other fertility factors and personal goals.

There is no single treatment that is right for everyone. Treatment plans should be individualised and reviewed if symptoms continue or change.

Do Fibroids or Endometriosis Affect Pregnancy?

Both conditions may influence fertility or pregnancy, but the impact varies considerably.

Fibroids and pregnancy

Many women with fibroids have healthy pregnancies. However, fibroids that distort the uterine cavity or have certain sizes and locations may affect conception or increase the risk of particular pregnancy complications.

If you are planning pregnancy and have been diagnosed with fibroids, your doctor can assess whether their location or size is likely to affect your reproductive plans and whether treatment should be considered.

Endometriosis and pregnancy

Endometriosis can make conception more difficult for some women, particularly when the ovaries, fallopian tubes or surrounding pelvic structures are affected.

However, many women with endometriosis conceive naturally. If you are having difficulty becoming pregnant, a fertility evaluation can help determine whether endometriosis or another factor may be contributing.

If you have either condition and are planning pregnancy, discuss your options with your gynaecologist before deciding on treatment. Some treatments are intended to manage symptoms rather than improve fertility, and surgery may have benefits and risks that need individual consideration.

When Should You See a Gynaecologist?

Do not dismiss persistent menstrual or pelvic symptoms simply because they occur around your period.

Consider arranging a gynaecological consultation if you experience:

• Period pain that disrupts work, studies, sleep or everyday activities.
• Heavy or prolonged menstrual bleeding.
• Bleeding between periods or after sexual intercourse.
• Persistent pelvic pain or a feeling of abdominal pressure.
• Pain during sex.
• Painful bowel movements or urination, particularly around menstruation.
• Difficulty becoming pregnant.
• Symptoms that persist, worsen or do not improve with treatment.

Seek urgent medical care for sudden, severe pelvic or abdominal pain, fainting, significant bleeding accompanied by weakness or dizziness, or severe pain with fever or vomiting.

Heavy menstrual bleeding can contribute to iron-deficiency anaemia, so persistent heavy periods should also be assessed.

Early evaluation can help identify the cause of your symptoms and determine whether monitoring, treatment or further investigation is needed.

Frequently Asked Questions (FAQs)

1. What is the main difference between fibroids and endometriosis?

Fibroids are non-cancerous growths that develop from the muscular tissue of the uterus. Endometriosis occurs when tissue similar to the uterine lining grows outside the uterus and may cause inflammation, pain and scar tissue.

2. Which is more painful: fibroids or endometriosis?

There is no universal answer. Endometriosis is often associated with severe period-related pelvic pain, while fibroids may cause heavy bleeding, cramps or pressure. Either condition can cause significant symptoms, and pain severity alone cannot establish a diagnosis.

3. Can an ultrasound detect both fibroids and endometriosis?

Ultrasound is commonly used to identify fibroids and can detect certain forms of endometriosis, including some ovarian endometriomas. However, a normal ultrasound does not rule out endometriosis.

4. Can fibroids turn into endometriosis?

No. Fibroids and endometriosis are different conditions. Fibroids do not transform into endometriosis, and endometriosis does not turn into fibroids.

5. Can you have fibroids and endometriosis at the same time?

Yes. Both conditions can occur together. A gynaecologist may need to assess symptoms and investigations carefully to identify which condition or conditions are contributing to discomfort or bleeding.

6. Do fibroids and endometriosis always require surgery?

No. Some women with fibroids need only monitoring, while others benefit from medication or procedures. Endometriosis may also be managed with pain relief or hormonal treatment, depending on symptoms and pregnancy plans. Surgery is considered when clinically appropriate.

7. Can fibroids or endometriosis cause infertility?

Both conditions can affect fertility in some women, but neither automatically causes infertility. The effect depends on factors such as fibroid location, the extent of endometriosis, age and other reproductive health considerations.

8. Can fibroids or endometriosis cause heavy periods?

Yes. Heavy menstrual bleeding can occur with fibroids and may also occur with endometriosis. Other conditions can cause heavy bleeding as well, so medical assessment may be needed to establish the cause.

Conclusion

Fibroids and endometriosis can both affect menstrual health, cause pelvic discomfort and sometimes influence fertility. However, they differ in their underlying causes, location and patterns of symptoms.

Fibroids are growths arising from the muscular tissue of the uterus, whereas endometriosis involves tissue similar to the uterine lining growing outside it. Although certain symptoms overlap, a gynaecological assessment and appropriate investigations can help clarify the diagnosis.

If you experience severe period pain, heavy bleeding, persistent pelvic discomfort or difficulty becoming pregnant, consider speaking with a gynaecologist. Understanding the cause of your symptoms is an important step towards choosing care that fits your needs and future plans.

Medical Disclaimer: This article is intended for general educational and awareness purposes only. It does not replace professional medical advice, diagnosis or treatment. Consult a qualified healthcare professional for an assessment of your symptoms and personalised treatment recommendations.