What Is Endometriosis? A Simple Guide to Understanding the Condition

Endometriosis is a chronic condition in which tissue similar to the lining of the uterus grows outside the uterus.

It can cause pain, inflammation, scar tissue, fertility challenges, and other symptoms—but the experience can look very different from one person to another.

For some people, symptoms are severe and disruptive. Others may have relatively mild symptoms or no obvious symptoms at all.

Where can endometriosis occur?

Endometriosis most commonly affects areas within the pelvis.

It may be found around the:

• Ovaries
• Fallopian tubes
• Outer surface of the uterus
• Pelvic lining
• Bladder
• Bowel or rectum

In some cases, endometriosis can occur outside the pelvis as well.

How common is endometriosis?

Endometriosis is not rare.

The World Health Organization estimates that approximately 10% of reproductive-age women worldwide—around 190 million people—are affected by endometriosis.

Yet many people live with symptoms for years before receiving a diagnosis.

What are common symptoms?

Symptoms vary considerably.

Some of the most commonly reported symptoms include:

• Severe or worsening period pain
• Chronic pelvic pain
• Pain during or after sex
• Pain during bowel movements
• Pain with urination, particularly around menstruation
• Heavy menstrual bleeding
• Bleeding between periods
• Abdominal bloating
• Fatigue
• Difficulty becoming pregnant

Endometriosis may also affect daily activities, work, school, relationships, sexual wellbeing, and emotional health.

One important thing to understand is that the amount of pain someone experiences does not necessarily reflect how extensive their endometriosis is.

Someone with relatively limited disease may experience significant pain, while someone with more extensive disease may experience fewer symptoms.

Is severe period pain normal?

Period discomfort is common, but pain that regularly prevents you from participating in normal activities deserves attention.

Examples include pain that causes you to:

• Miss work or school
• Cancel plans regularly
• Stay in bed because of pain
• Experience vomiting or faintness
• Depend heavily on pain medication
• Avoid sex because of pain
• Experience significant bowel or bladder pain around your period

Severe or persistent pelvic pain can have many possible causes. Endometriosis is one possibility, but it is not the only one.

A healthcare professional can help evaluate the symptoms and determine what may be causing them.

What causes endometriosis?

Researchers still do not completely understand why endometriosis develops.

Several theories have been proposed, and ongoing research is examining genetic, hormonal, immune-system, inflammatory, and other biological factors.

There is currently no single explanation that accounts for every case.

That is one reason endometriosis remains an important area of medical research.

How is endometriosis diagnosed?

Diagnosis usually begins with a conversation about symptoms and medical history.

A healthcare professional may ask about:

• When pain occurs
• Whether symptoms are connected to the menstrual cycle
• How severe symptoms are
• Whether symptoms affect work, school, sleep, relationships, bowel movements, urination, or sexual activity
• Fertility concerns
• Family history
• Previous treatments

Depending on the situation, evaluation may also include a physical examination and imaging such as ultrasound or MRI.

In some circumstances, laparoscopic surgery may be used to visualize endometriosis directly and obtain tissue for confirmation.

Importantly, current guidance recognizes that treatment decisions may sometimes begin based on symptoms and imaging without waiting for surgery.

Is there a cure?

There is currently no definitive cure for endometriosis.

Treatment focuses on managing symptoms, improving quality of life, supporting fertility goals when relevant, and addressing the person's individual needs.

Treatment options may include:

• Pain-management medications
• Hormonal medications
• Surgery
• Fertility treatment
• Pelvic-floor or other physical therapy in appropriate situations
• Multidisciplinary pain management

The right approach can differ significantly from one person to another.

Endometriosis and fertility

Endometriosis can be associated with fertility difficulties, but having endometriosis does not automatically mean someone will be unable to become pregnant.

Some people with endometriosis conceive without fertility treatment, while others may benefit from medical or fertility support.

Anyone concerned about fertility should discuss their individual circumstances with a qualified healthcare professional.

Why can diagnosis take so long?

Endometriosis can be difficult to recognize because symptoms overlap with many other conditions.

Period pain may also be normalized or dismissed.

People may hear things such as:

“Periods are supposed to hurt.”

“Everyone gets cramps.”

“You're just sensitive to pain.”

But persistent or severe symptoms deserve thoughtful evaluation.

The World Health Organization reports that the average time to diagnosis can range from approximately 4 to 12 years.

Improving awareness—among patients, families, schools, workplaces, and healthcare professionals—is therefore an important part of improving endometriosis care.

When should you consider talking with a healthcare professional?

Consider seeking medical advice if menstrual or pelvic symptoms are:

• Severe
• Getting worse
• Affecting your daily activities
• Interfering with work or school
• Affecting relationships or sexual activity
• Associated with bowel or bladder pain
• Accompanied by very heavy bleeding
• Creating fertility concerns
• Simply worrying you

You do not need to determine whether you have endometriosis before asking for help.

Your role is to describe what you are experiencing.

A healthcare professional's role is to help investigate why.

Preparing for the conversation

It can help to keep notes about symptoms before an appointment.

You might track:

• When symptoms happen
• How long they last
• How severe they feel
• Whether they occur around your period
• Bowel or bladder symptoms
• Bleeding patterns
• Medications you've tried
• Activities you've had to miss
• Questions you want to ask

Marigold Circle's upcoming Appointment Prep tool will help visitors organize this information into a simple conversation guide to take to a healthcare appointment.

One thing to remember

Living with unexplained pain or other symptoms can be frustrating, especially when answers do not come quickly.

Learning what endometriosis is does not mean diagnosing yourself.

It means becoming better informed so you can recognize when symptoms deserve attention, ask useful questions, and participate more confidently in conversations about your health.