What is Endometriosis? Symptoms, Causes, and Treatment

12 min read

Endometriosis is a chronic gynecological disease that occurs when endometrial tissue, the lining of the uterus, implants outside the uterus in the ovaries, fallopian tubes, peritoneum, and surrounding tissues. Normally found only within the uterus, this tissue, when implanted in the wrong locations, responds to hormonal changes similar to the menstrual cycle, causes bleeding, and can lead to inflammation and adhesions over time.

Endometriosis lesions, particularly those located in the ovaries, are called "chocolate cysts." This is because the dark brown fluid that accumulates within the cyst over time resembles melted chocolate. While these ovarian cysts can negatively affect egg quality, adhesions developing in the fallopian tubes and abdominal cavity can also disrupt the normal functioning of the tubes, making pregnancy more difficult.

Endometriosis is a disease that can cause significant problems such as severe menstrual cramps, chronic pelvic pain, pain during intercourse, and infertility. However, because the symptoms are often mistaken for "normal menstrual pain," the diagnostic process can be delayed. Therefore, many women only learn they have the disease when they have difficulty conceiving.

Endometriosis, thought to affect 1 in 10 women of reproductive age, is more common in women undergoing IVF treatment or experiencing infertility problems. The definitive diagnosis is often made using a minimally invasive surgical method called laparoscopy. A thin camera inserted through the navel allows for evaluation of the abdominal cavity and direct visualization of endometriosis lesions.

Early diagnosis and the right treatment approach are crucial for both reducing pain and preserving fertility. Therefore, it is recommended that women experiencing severe menstrual pain or who have been unable to conceive for a long time be evaluated for endometriosis.

So, what causes endometriosis? What are its symptoms? Is treatment possible? Here are the answers to frequently asked questions about endometriosis…

What is endometriosis?

It is the process by which endometrium, the tissue that normally lines the inside of the uterus and should only be found inside, implants in organs outside the uterus, such as the ovaries, fallopian tubes, peritoneum, intestines, bladder, and connective tissues surrounding the uterus.

What is a chocolate cyst?

Chocolate cysts, medically known as 'endometrioma' , are a type of cyst that forms when tissue similar to the endometrium lining the uterus implants in the ovaries. This is one of the most common forms of endometriosis.

Normally, the uterine lining is shed and expelled from the body during menstruation. However, endometriosis lesions in the ovaries also bleed each month due to hormonal changes. Because this blood cannot be expelled, it accumulates within the cyst over time and becomes a dark brown, thick fluid. Due to its resemblance to melted chocolate, it is commonly called a "chocolate cyst."

Chocolate cysts, especially those that reach large sizes or affect both ovaries, can negatively impact ovarian reserve and fertility. Therefore, early diagnosis and regular follow-up are of great importance.

Where is endometriosis most commonly found?

Although endometriosis can occur in different parts of the body, it most commonly appears in the following areas:

Ovaries
Fallopian tubes
Peritoneum
Connective tissues surrounding the uterus
Intestines
Bladder
Vagina and rectovaginal area

More rarely, it can also be found in different organs such as the navel, old surgical suture sites, diaphragm, spleen, eye, brain, and even the lung.

Ovarian involvement occurs in approximately 60-75% of cases.

What causes endometriosis?

The exact cause of endometriosis is still not fully known. Although it was first described in 1860, the mechanisms by which the disease develops continue to be investigated today.

The main theories accepted in the scientific community are as follows:

1. Retrograde Menstruation: According to the most common theory, some menstrual blood flows back into the abdominal cavity through the fallopian tubes. Endometrial cells carried during this process can implant in the peritoneum or ovaries, forming foci of endometriosis.

2. Genetic Predisposition : Women whose mothers or sisters have endometriosis have a higher risk of developing the disease compared to the general population.

3. Immune System Problems: Normally, the immune system should destroy these cells, but in some women, the immune system may not be able to provide an adequate response.

4. Hormonal and Environmental Factors: High levels of estrogen hormone can promote the development of endometriosis. It is also thought that some environmental toxins and chemicals may pose a risk.

5. Chronic Inflammation: Inflammation around endometriosis lesions can contribute to both pain and infertility. Some studies published in 2025 and 2026 have shown that gut microbiota and inflammatory processes may also play a role in disease development. Therefore, endometriosis is now considered not only a gynecological disease but also a systemic inflammatory condition.

What are the symptoms of endometriosis?

Endometriosis may sometimes not cause any symptoms. However, the most common symptoms are:

Severe Menstrual Pain: Painful menstruation that affects daily life is one of the most important symptoms.
Chronic Groin and Lower Back Pain: Long-lasting groin, abdominal, or lower back pain may occur.
Painful Sexual Intercourse: Pain may be felt during intercourse.
Infertility: Endometriosis can cause adhesions in the fallopian tubes and damage to the ovaries, making pregnancy more difficult.
Bowel and Urinary Complaints: Symptoms may include constipation, bloating, painful defecation, frequent urination, and burning during urination.
Chronic Fatigue and Depression: The persistent pain and inflammation caused by the illness can lead to weakness, difficulty concentrating, and a depressed mood.

How is endometriosis diagnosed?

Endometriosis, despite being one of the leading causes of chronic pelvic pain and infertility in women, is often diagnosed late. Many women consider the severe menstrual pain they experience for years to be "normal," which prolongs the diagnostic process. However, early diagnosis is crucial for controlling pain, improving quality of life, and preserving fertility.

So how is endometriosis diagnosed? Can chocolate cysts be seen on ultrasound? What tests are performed? Here's what you need to know about the endometriosis diagnostic process…

1. Detailed History Taking and Symptom Assessment (Anamnesis) : The first and most important step in an accurate diagnostic process is carefully listening to the patient's complaints. Your doctor will ask you the following questions to trace the signs of the disease:

How long your pain has been going on, exactly where you feel it, and its connection to your menstrual cycle,
Whether you experience pain during sexual intercourse, urination, or defecation,
Your past surgical operations,
Difficulty conceiving (infertility) or a history of miscarriage,
A history of endometriosis in other women in your family (mother, sister, etc.).

Important Note: Severe pain that recurs during each menstrual cycle and restricts daily life should strongly suggest endometriosis.

2. Physical and Gynecological Examination: A gynecological examination helps us understand anatomical changes in the pelvic region. During this examination, the following findings may increase suspicion of endometriosis:

Restricted uterine movements
Tenderness behind the uterus
Painful nodule or lump felt
Swelling in the ovarian area
However, because some foci of the disease may be very small or deeply located, examination alone does not provide a definitive diagnosis.

3. Ultrasonography (USG) Imaging : Vaginal ultrasonography is one of the most frequently used first-step and practical imaging methods in the evaluation of endometriosis. "Chocolate cysts," especially those forming in the ovaries, give a very typical image on ultrasound.

During the ultrasound, the following might be observed:

A thick-walled structure with distinct and regular boundaries.
Its interior is filled with a thick, homogeneous, and opaque (echogenic) liquid.
Adhesions around the ovaries
Restricted uterine movements

In some advanced cases, nodules around the intestines or bladder may also be visualized.

However, superficial endometriosis lesions may not always be detectable on ultrasound. Therefore, a normal ultrasound result does not necessarily mean that the disease has been ruled out.

4. Magnetic Resonance Imaging (MRI): Pelvic MRI plays a vital role, especially in cases called "deep infiltrative endometriosis," which progresses to deeper tissues.

Thanks to MRI we can find:

Whether the disease has spread to surrounding organs such as the bladder, intestines, or ureter (urinary tract) is determined with millimeter precision.
Deep pelvic adhesions
By providing the surgeon with a clear roadmap before the surgical procedure, it increases the success rate of the operation.

5. Blood Tests and Tumor Markers (CA-125): In the presence of endometriosis, an increase in the levels of certain proteins in the blood may be observed. The most frequently used laboratory test for this purpose is CA-125.

CA-125 levels may be elevated in some endometriosis patients and may be related to the severity of the disease. They can also be used to monitor treatment. However, they are not diagnostic on their own. A normal CA-125 level does not mean the absence of endometriosis. In some cases, a CA 19-9 test may also be requested for additional evaluation. These markers are not diagnostic alone, but rather helpful in monitoring the course of the disease and response to treatment.

6. Laparoscopy, Definitive Diagnostic Method: The definitive and unambiguous diagnosis of endometriosis is achieved through laparoscopy, a minimally invasive surgical procedure. laparoscopy It is inserted through a small incision around the navel, and a thin camera is used to directly observe the inside of the abdomen.

During this procedure: Endometriosis foci are directly visualized, and chocolate cysts can be evaluated. The extent of adhesions is determined, and biopsies can be taken if necessary.

One of the most important advantages of laparoscopy is that it allows for both diagnosis and treatment in the same operation. During laparoscopy, endometriosis lesions can be removed, adhesions can be released, and even chocolate cysts can be removed. Therefore, laparoscopy is both a diagnostic and therapeutic method.

Who is more likely to get endometriosis?

Some women are at higher risk:

Those with a family history of endometriosis
Women who have never given birth
Those who started menstruating at an early age
Those who enter menopause late
Those with high estrogen exposure
People with a low body mass index

Can endometriosis cause infertility?

Endometriosis can affect the reproductive system in various ways, potentially reducing the chances of pregnancy:

It can reduce ovarian reserve.
It can disrupt ovulation functions.
It can cause blockages in the fallopian tubes.
It can prevent sperm and egg from uniting.
It can make it more difficult for the embryo to implant in the uterus.
It can negatively affect embryo development.
It can cause adhesions in the pelvic region.

Endometriomas, or chocolate cysts, which particularly form in the ovaries, can damage healthy egg tissue, leading to a decrease in the number of eggs. This can eventually cause a decline in ovarian reserve.

When endometriosis progresses, it can cause inflammation and scar tissue formation in the abdominal cavity. This can create adhesions around the fallopian tubes, preventing the egg from reaching them. In some patients, the tubes may become completely blocked. This condition is called "tubal obstruction" and can significantly reduce the chances of natural pregnancy.

Endometriosis can affect not only the eggs and fallopian tubes, but also the uterine lining. Certain inflammatory substances (cytokines and humoral factors) secreted from the disease lesions can negatively impact embryonic development and implantation in the uterus. Therefore, in some women, even if fertilization occurs, the pregnancy may not progress healthily.

Are all women with endometriosis infertile?

No, many women diagnosed with endometriosis can conceive naturally. However, the chances of pregnancy may decrease if the disease is advanced, ovarian reserve is reduced, or there is significant damage to the fallopian tubes.

The risk of infertility may increase, especially in the following situations:

Advanced endometriosis
Large chocolate cysts
Both ovaries are affected.
Presence of severe adhesions.
Long-term inability to conceive

How is endometriosis treated?

Endometriosis treatment varies depending on the patient's age, desire for children, the extent of endometriosis, and the severity of the symptoms . There are two main approaches to treatment:

1. Medical (Drug) Treatment:

Pain relievers: Anti-inflammatory pain relievers can be used to reduce severe menstrual pain. These medications do not completely eliminate the condition but help control symptoms.
Birth control pills
Progesterone treatments
Hormone-suppressing drugs: Endometriosis lesions are affected by the hormone estrogen. Therefore, hormone-suppressing treatments may be used.

These treatments aim to suppress the activity of endometriosis lesions by reducing or stopping menstrual bleeding. However, hormone therapies do not provide a permanent solution for patients who wish to become pregnant. Symptoms may reappear when the medication is stopped. Endometriosis is not a disease that can be completely eradicated. Treatment should be planned individually for each patient.

2. Surgical Treatment :

Chocolate cysts are not always surgically treated. Surgery for chocolate cysts can reduce a patient's ovarian reserve. Therefore, surgery is only considered if there is a genuine need. The goal of surgery is:

To remove adhesions
Removing chocolate cysts
The goal is to remove the endometriosis foci.

Careful surgery to preserve ovarian reserve is of great importance, especially for women who wish to have children.

Can endometriosis completely disappear?

Endometriosis is a chronic disease that can recur. However, with early diagnosis, regular follow-up, and appropriate treatment, pain can be controlled, thus improving the patient's quality of life and chances of pregnancy.

Endometriosis is not just about menstrual pain. It is a serious health problem that can affect a woman's physical, social, and psychological life. It is especially important for women experiencing severe menstrual pain not to consider this normal and to consult a gynecologist.

Today, thanks to advancements in diagnostic methods, modern surgical techniques, and in-vitro fertilization (IVF) treatments, it is possible to achieve successful outcomes in patients with endometriosis.

The Relationship Between Endometriosis and In Vitro Fertilization

Endometriosis is closely associated with infertility. The disease can reduce ovarian reserve and affect egg quality. It can also make it more difficult for embryos to implant. While natural pregnancy is possible in some patients, in others, in-vitro fertilization (IVF) may be necessary.

Especially:

Advanced endometriosis
Low ovarian reserve
The tubes are affected.
Long-term infertility

In these cases, in-vitro fertilization (IVF) can be an important option.

Current studies show that personalized treatment planning increases success rates.

Conclusion

Endometriosis is more than just "menstrual pain." It is a significant health problem that can affect a woman’s quality of life, social life, and fertility. It is especially important for women experiencing severe menstrual pain to not consider this normal and to seek professional evaluation.

Today, thanks to advancements in diagnostic methods, modern surgical techniques, and in-vitro fertilization (IVF), it is possible to achieve successful outcomes in patients with endometriosis. Early diagnosis and a personalized treatment approach play a crucial role in both pain control and increasing the chances of pregnancy.

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