Endometriosis and Infertility: Understanding the Connection

Endometriosis is a condition in which tissue similar to the lining of the uterus grows outside the uterus, often around the ovaries, fallopian tubes or other areas of the pelvis. It can cause inflammation, pelvic pain, painful periods and, in some women, fertility difficulties.

The endometriosis meaning is often misunderstood because the condition can vary greatly from one woman to another. Some women have severe symptoms, while others have mild disease or no obvious symptoms until they undergo fertility evaluation. Understanding what is endometriosis, where it can occur, how it is diagnosed and treated, and how it may affect conception can help women make more informed decisions about reproductive care.

What Is Endometriosis?

To define endometriosis simply, it is a condition in which tissue similar to the endometrium, the lining inside the uterus, grows outside the uterine cavity.

This tissue may be found on or around:

• the ovaries
• fallopian tubes
• pelvic lining
• tissues behind the uterus
• other structures within the pelvis

Unlike the uterine lining, this tissue is outside the uterus and can contribute to inflammation, irritation, scar tissue and adhesions.

The endometriosis meaning does not refer to cancer, and the condition is different from endometrial hyperplasia, which involves abnormal thickening of the lining inside the uterus.

Some women with endometriosis experience significant pain, while others have minimal symptoms. In some cases, difficulty conceiving may be the first reason the condition is suspected.

Understanding Endometriosis and How It Develops

The exact biological process behind endometriosis is not fully understood.

Endometrial-like tissue outside the uterus can respond to hormonal changes during the menstrual cycle. This may trigger repeated inflammation in the surrounding tissues.

Over time, inflammation may contribute to:

• scar tissue
• adhesions
• ovarian cysts called endometriomas
• changes in normal pelvic anatomy

Adhesions can cause pelvic organs to become less mobile or alter the normal relationship between the ovaries and fallopian tubes.

Several theories have been proposed to explain why endometriosis develops, but no single explanation accounts for every case.

For this reason, it is more accurate to describe endometriosis as a complex condition influenced by biological, hormonal, genetic and immune factors rather than attributing it to one definite cause.

Where Can Endometriosis Occur in the Body?

Endometriosis most commonly affects structures within the pelvis.

It may occur on:

• ovaries
• fallopian tubes
• pelvic peritoneum
• ligaments supporting the uterus
• tissues behind or around the uterus
• areas near the bowel or bladder

When endometriosis affects the ovaries, it can sometimes form cysts known as endometriomas.

Lesions around the fallopian tubes or extensive pelvic adhesions may interfere with normal egg pickup or movement through the reproductive tract.

The location of endometriosis can influence symptoms, but symptom severity does not always match disease extent. A woman with relatively limited disease may have significant pain, while another with more extensive disease may have few symptoms.

Types of Endometriosis

Endometriosis may be described according to the location and depth of the lesions.

Superficial Peritoneal Endometriosis

This form involves relatively shallow lesions on the lining of the pelvic cavity.

The lesions may occur in different areas of the pelvis and can contribute to inflammation and pain.

Ovarian Endometriosis

Endometriosis affecting the ovaries may form cysts called endometriomas.

These cysts can vary in size and may become relevant when assessing ovarian reserve, fertility treatment or whether surgery is appropriate.

Deep Endometriosis

Deep endometriosis involves lesions that extend more deeply into pelvic tissues.

It may affect structures around the uterus, bowel, bladder or pelvic ligaments and can be associated with significant pelvic pain.

The type and extent of disease are considered alongside symptoms, age and fertility plans when treatment is discussed.

Symptoms of Endometriosis

Endometriosis symptoms can vary considerably, and some women may have little or no obvious discomfort.

Common symptoms of endometriosis include:

• painful periods
• chronic pelvic pain
• lower abdominal or back pain
• pain during or after intercourse
• painful bowel movements during periods
• pain during urination around menstruation
• heavy menstrual bleeding in some women
• bloating or gastrointestinal discomfort
• difficulty conceiving

Painful periods are among the better-known endometriosis signs, particularly when pain is severe enough to interfere with daily activities.

However, the signs of endometriosis are not specific to the condition. Adenomyosis, fibroids, ovarian cysts, pelvic inflammatory disease and gastrointestinal conditions may produce similar symptoms.

Some women discover endometriosis only while being investigated for infertility.

Importantly, the amount of pain does not reliably indicate disease severity. Mild disease can sometimes be painful, while more extensive endometriosis may produce surprisingly few symptoms.

Causes and Risk Factors of Endometriosis

The exact endometriosis causes remain uncertain.

Researchers have proposed several possible mechanisms, including movement of menstrual tissue through the fallopian tubes into the pelvis, altered immune responses, genetic influences and transformation of certain pelvic cells.

However, none of these theories fully explains every case.

When asking what causes endometriosis, it is therefore important to distinguish possible biological mechanisms from proven causes.

Possible endometriosis risk factors may include:

• family history of endometriosis
• certain menstrual characteristics
• reproductive age
• individual genetic susceptibility

Having a risk factor does not mean that a woman will definitely develop the condition.

Likewise, endometriosis can occur without any obvious risk factor.

The causes of endometriosis are still being studied, and lifestyle choices should not be presented as the sole explanation for why the disease develops.

What Is the Link Between Endometriosis and Infertility?

Endometriosis and infertility are associated, but endometriosis does not automatically mean that a woman will be unable to conceive.

The condition may affect fertility in several ways.

Changes in Pelvic Anatomy

Scar tissue and adhesions may change the normal relationship between the ovaries and fallopian tubes.

This can make it more difficult for the fallopian tube to pick up an egg after ovulation.

Inflammation

Endometriosis can create an inflammatory environment within the pelvis.

This may potentially affect sperm function, fertilisation, egg-sperm interaction or other reproductive processes.

Ovarian Factors

Endometriomas may affect the ovaries, and both the disease itself and ovarian surgery in selected cases can influence ovarian reserve.

Tubal Factors

Adhesions around the fallopian tubes may interfere with normal tubal movement or function.

Other Fertility Factors

Age, ovarian reserve, sperm quality and other reproductive conditions also influence conception.

So, how does endometriosis affect fertility? The effect differs greatly depending on disease location, severity and the woman’s overall fertility profile. Some women conceive naturally, while others may need fertility treatment.

How Is Endometriosis Diagnosed?

An endometriosis diagnosis usually begins with symptoms, medical history and a clinical evaluation.

The assessment may include:

Medical History

A doctor may ask about:

• menstrual pain
• pelvic pain
• pain during intercourse
• bowel or urinary symptoms
• previous pregnancies
• fertility history
• family history

Pelvic Examination

A pelvic examination may sometimes identify tenderness, reduced mobility or masses, although a normal examination does not rule out endometriosis.

Ultrasound

Transvaginal ultrasound may identify ovarian endometriomas and some forms of deep endometriosis.

However, superficial disease may not always be visible on routine imaging.

MRI

MRI may be useful in selected cases when more detailed mapping of pelvic disease is needed.

Laparoscopy and Biopsy

Laparoscopy allows direct visualisation of the pelvis and may be used in selected patients when surgery is clinically indicated.

An endometriosis biopsy involves obtaining tissue during a surgical procedure for laboratory examination. Biopsy may help confirm the nature of a lesion, although not every woman needs surgery simply to establish a diagnosis for endometriosis.

The diagnostic approach depends on symptoms, imaging findings and fertility plans.

Endometriosis Treatment Options

Endometriosis treatment depends on:

• severity of symptoms
• location of disease
• age
• ovarian reserve
• desire for pregnancy
• previous treatment
• other fertility factors

There is no single treatment suitable for every woman.

Pain Management

Pain-relieving medicines may be used to manage menstrual or pelvic discomfort.

They can help control symptoms but do not remove endometriosis.

Hormonal Treatment

Hormonal medicines can suppress ovarian hormonal activity and reduce endometriosis-related pain in women who are not currently trying to conceive.

These treatments generally prevent or reduce ovulation while they are being used, so they are not fertility treatments for women actively trying for pregnancy.

Surgery

Surgery may be considered in selected cases to remove endometriosis lesions, endometriomas or adhesions.

The decision requires care, particularly for ovarian endometriomas, because surgery can sometimes affect ovarian reserve.

Fertility Treatment

When pregnancy is the main goal, treatments for endometriosis may include timed conception, IUI treatment or IVF treatment, depending on age, ovarian reserve, disease severity and other fertility factors.

ICSI treatment may also be used when there is an appropriate sperm-related or fertilisation indication.

Can Women with Endometriosis Get Pregnant Naturally?

Yes. Many women with endometriosis can become pregnant naturally.

The chance of conception depends on several factors, including:

• age
• ovarian reserve
• severity and location of disease
• whether the fallopian tubes are open and functioning
• whether adhesions distort pelvic anatomy
• sperm quality
• duration of infertility

Mild endometriosis does not necessarily prevent natural conception.

However, more extensive disease, significant adhesions or ovarian involvement may make conception more difficult.

Women with regular cycles can still have endometriosis, so a normal menstrual cycle does not rule it out.

If pregnancy is not occurring within the expected timeframe, a fertility evaluation can help determine whether continued natural attempts, IUI, IVF or another approach is appropriate.

Fertility Treatment for Endometriosis

The fertility treatment plan is based on the complete clinical picture rather than the diagnosis alone.

For selected women with minimal or mild disease, natural conception or IUI may be considered depending on age and other fertility factors.

IVF may be recommended when:

• fallopian tubes are affected
• ovarian reserve is reduced
• infertility has continued despite other treatment
• age makes further delay less appropriate
• pelvic anatomy is significantly altered
• additional male-factor infertility is present

During IVF, eggs are retrieved directly from the ovaries and fertilised in the laboratory, reducing dependence on normal tubal function.

Embryos may be transferred in the same treatment cycle or preserved for a later frozen embryo transfer when clinically appropriate.

The presence of endometriosis does not mean that every woman automatically needs IVF.

Preventing Complications and Managing Recurrence

There is currently no guaranteed method to prevent endometriosis from developing.

Management therefore focuses on controlling symptoms, protecting reproductive health and reviewing recurring or changing symptoms.

Women with known endometriosis may benefit from:

• regular follow-up when advised
• monitoring pelvic pain
• seeking care for worsening symptoms
• discussing fertility plans early when pregnancy is desired
• reviewing ovarian reserve before some ovarian surgeries
• following the recommended medical treatment plan

Endometriosis can recur after treatment, including after surgery.

Recurrence does not necessarily mean that treatment has failed. The condition can remain hormonally active over time, so ongoing management may be needed depending on symptoms and reproductive plans.