Thoracic endometriosis is a rare condition that can cause chest pain and shortness of breath around the time of your period. It can also lead to life threatening complications like a collapsed lung.

Thoracic endometriosis occurs when endometrial tissue grows inside your chest cavity, in or around your lungs.

In a typical case of endometriosis, patches of endometrial tissue develop in your pelvic area and lower abdomen. The tissue — which is not supposed to grow outside the uterus — might grow on the ovaries or the bowels.

When endometrial tissue grows in areas beyond the pelvis, it’s known as extragenital endometriosis.

Although thoracic endometriosis is rare, it is the most common type of extragenital endometriosis. It can cause chest pain, cough, and shortness of breath. It may even lead to life threatening complications, such as a collapsed lung.

Language matters

You’ll notice that the language used in this article to share stats and other data points is pretty binary.

Unfortunately, the studies and surveys referenced in this article didn’t report data on, or include, participants who were transgender, nonbinary, or gender nonconforming.

Was this helpful?

Endometrial tissue is the tissue that lines the inner walls of the uterus. Endometriosis is when endometrial-like tissue grows outside the uterus, where it doesn’t belong.

In most people with endometriosis, patches of endometrial tissue grow in areas near the uterus, like the ovaries, bladder, or bowels.

Thoracic endometriosis is a rare — and possibly underdiagnosed — form of endometriosis. It occurs when endometrial-like tissue grows in your chest, which is also known as your thoracic cavity.

Endometriosis affects about 6–10% of reproductive-aged women, according to a 2019 review of research. Among those women, it’s estimated that about 12% develop endometrial growths in areas beyond the pelvic and abdominal cavities.

When endometrial tissue grows in other areas, like the chest, it is known as extragenital endometriosis.

The thoracic cavity is actually the most common extragenital area where you might find endometrial tissue growing.

Research suggests that many women who have thoracic endometriosis also have the more common pelvic form of endometriosis. Between 50–84% of women with thoracic endometriosis also have pelvic endometriosis.

While thoracic endometriosis can develop spontaneously, it typically affects people with a history of severe pelvic endometriosis.

Experts currently believe that thoracic endometriosis is often a progression of pelvic endometriosis. In other words, the endometrial growths appear first in the pelvic area and later develop in the chest area.

People tend to be a bit older when they develop symptoms of thoracic endometriosis. According to the 2019 review, people have symptoms of thoracic endometriosis about 5 to 7 years after developing symptoms of pelvic endometriosis.

If you have a history of endometriosis and you regularly develop a cough or chest pain during your menstrual period, consider reaching out to a doctor.

Like pelvic endometriosis, symptoms of thoracic endometriosis tend to get worse during menstruation.

The symptoms of thoracic endometriosis depend largely on the location of the endometrial growths. But cyclic episodes of chest pain, shortness of breath, and cough are common.

Here’s why you could be experiencing those symptoms:

Catamenial pneumothorax (CP)

Research in 2021 suggests that the most common manifestation of thoracic endometriosis is a condition called catamenial pneumothorax (CP).

CP is a collapsed lung that occurs around the time of menstruation — anywhere from one day before to 72 hours afterward. The research states that about 70% of people with symptoms of thoracic endometriosis experience CP.

How do people develop CP? Endometrial tissue can cause holes to develop in the diaphragm, which allows air and fluid into the space around the lung, causing a lung to collapse. More than 97% of cases affect the right lung.


A hemothorax happens when blood pools in the pleural cavity, which is the space between your lung and the chest wall. The pressure this causes can cause your lung to collapse.

A catamenial hemothorax happens when a hemothorax occurs cyclically around the time of menstruation.

Research suggests that catamenial hemothorax may develop in up to 15% of people with thoracic endometriosis.


Catamenial hemoptysis is recurrent bleeding or hemorrhaging that occurs in the lungs in combination with the menstrual cycle.

Hormonal changes are believed to trigger bleeding in the endometrial tissue in the lung parenchyma, which is the part of the lung involved with the exchange of gases.

As a result of the bleeding, catamenial hemoptysis can lead to chronic anemia.

Lung nodules

According to 2021 research, about 6% of people with thoracic endometriosis develop lung nodules. When these small abnormal growths, or nodules, appear in your lungs, they can cause coughing, pain, and shortness of breath.

Pelvic pain — really severe menstrual cramps in your lower belly or lower back — is the most common symptom of endometriosis.

However, not everyone with endometriosis will experience severe pain or any pain at all. Some people with endometriosis do not have any symptoms.

When people do have symptoms, they typically happen during menstruation and include:

Experts don’t know exactly what causes thoracic endometriosis, but there are a number of theories.

Some researchers have suggested that it could be a combination of factors.

The oldest theory is the retrograde menstruation theory, which supposes that endometrial cells inadvertently move through the fallopian tubes toward other areas of the body. The theory is that once those cells migrate beyond the uterus, they attach themselves to other surfaces and begin growing.

As researchers in a 2021 case report admit, it can be challenging to diagnose a case of thoracic endometriosis. First of all, it’s rare, so doctors aren’t used to seeing it. It can also present with nonspecific symptoms, like cough, that can be mistaken for other conditions.

Your doctor may choose to use one or several kinds of imaging tests in order to diagnose a case of thoracic endometriosis. This might include:

The various tests can be useful for looking at certain things. For example, research suggests that chest X-rays and CT scans are well suited to identify pneumothorax and hemothorax.

Meanwhile, an MRI may be more useful for finding endometrial growths in the chest cavity.

Just as there is no cure for pelvic endometriosis, there is currently no cure for thoracic endometriosis. But you can manage your symptoms.

Depending on the severity of your situation — and your symptoms — your doctor may start out by discussing medical treatment first. If medical treatment is not enough, you may want to consider surgical options.

While surgery can relieve symptoms for some people, it is possible that you may experience some recurrence of symptoms.

Medical treatment

Since elevated hormone levels can trigger endometriosis symptoms, your doctor may suggest medications to regulate or suppress those hormones. Hormone suppression therapy may also prevent the spread or growth of endometrial tissue.

Some of the medications for thoracic endometriosis are the same ones used to treat regular endometriosis. These include:

Surgical treatment

Depending on your symptoms or if medical treatments do not relieve symptoms, you and your doctor may consider surgery.

Typically this will involve a minimally invasive procedure in which the surgeon goes in and removes the patches of endometrial tissue. In some cases, you may still continue taking hormonal therapy after surgery.

Some people even undergo one multidisciplinary surgery to treat both pelvic and thoracic endometriosis: a procedure that combines video laparoscopy (VL) with video-assisted thoracoscopic surgery (VATS).

Thoracic endometriosis is a rare condition that can cause pain, cough, and shortness of breath. Symptoms typically worsen around the time of your period.

If you experience these symptoms, especially if you have a history of endometriosis symptoms, you should reach out to a doctor about your concerns.