Endometriosis is a painful condition in which tissue that normally lines your uterus (called endometrial tissue) grows in other parts of your abdomen and pelvis.

Diaphragmatic endometriosis occurs when this endometrial tissue grows into your diaphragm.

Your diaphragm is the dome-shaped muscle beneath your lungs that helps you breathe. When endometriosis involves the diaphragm, it usually affects the right side.

When endometrial tissue builds up within the diaphragm, it reacts to the hormones of your menstrual cycle, just as it does in your uterus. Women with diaphragmatic endometriosis almost always have endometriosis in their pelvis, too.

Diaphragmatic endometriosis is much less common than other forms of the disease that typically affect the ovaries and other pelvic organs. It’s estimated that about of women have endometriosis. And up to of women with endometriosis experience difficulties getting pregnant. The diaphragm is believed to affect just of women who have surgery for the disease.

Diaphragmatic endometriosis may not cause any symptoms.

But you might experience pain in these areas:

  • chest
  • upper abdomen
  • right shoulder
  • arm

This pain usually occurs around the time of your period. It can be intense, and it may get worse when you breathe or cough. In rare cases, it can lead to a .

If endometriosis is in parts of your pelvis, you could also have symptoms like:

  • pain and cramps before and during your periods
  • pain during sex
  • heavy bleeding during or in between periods
  • fatigue
  • nausea
  • diarrhea
  • difficulty getting pregnant

Doctors don’t know exactly what causes diaphragmatic or other types of endometriosis. The most accepted theory is retrograde menstruation.

During menstrual periods, blood can flow backward through the fallopian tubes and into the pelvis, as well as out of the body. Those cells can then travel throughout the abdomen and pelvis and up into the diaphragm.

However, research has shown that most women experience retrograde menstruation. Yet most women don’t develop endometriosis, so the immune system is suspected to play a role.

Other possible contributors to endometriosis likely include:

  • Cell transformation. Cells affected by endometriosis respond differently to hormones and other chemical factors.
  • Genetics. Endometriosis has been shown to run in families.
  • Inflammation. Certain substances that have a role in inflammation are found in high numbers in endometriosis.
  • Fetal development. These cells might grow in various places since before birth.

Diaphragmatic endometriosis may not cause symptoms. Even if you do have symptoms, you might mistake them for something else — like a pulled muscle.

Because this condition is so rare, your doctor may not recognize the symptoms either. One important clue can be if the symptoms are typically worse around your period.

Sometimes doctors discover endometriosis while doing surgery to diagnose another condition.

If you’re experiencing symptoms or suspect that you may be affected by endometriosis, talk with your doctor about the best steps towards diagnosis.

They can use MRI testing to determine whether endometrial tissue has grown in your diaphragm and diagnose this condition. MRI scans and ultrasounds can be useful for finding endometriosis in your pelvis.

Often the best way to diagnose diaphragmatic endometriosis is with laparoscopy. This involves your surgeon making a few small cuts in your abdomen. A scope with a camera on one end is inserted to help your doctor see your diaphragm and find the endometrial tissue. Small samples of tissue, called biopsies, are usually collected and sent to the lab in order to look at these cells under a microscope.

Once your doctor identifies endometrial tissue, they’ll make a diagnosis based on the location, size, and amount of this tissue.

Below is the most commonly used staging system for endometriosis, established by the American Society of Reproductive Medicine. However, these stages aren’t based on symptoms. Symptoms can be significant even with stage 1 or stage 2 disease.

They include:

  • Stage 1: Minimal — small patches in the pelvis, limited areas, and organs
  • Stage 2: Mild — more areas in the pelvis than stage 1, but with minimal scarring
  • Stage 3: Moderate — organs of the pelvis and abdomen are affected with scarring
  • Stage 4: Severe — widespread lesions affecting organ appearance with scarring

Scientists are currently working to establish other methods for describing endometriosis, especially in cases where deeper tissues are involved. The newer system is still in development.

If you don’t have symptoms, your doctor might recommend that you wait to treat your endometriosis. Your doctor will check you regularly to see if symptoms develop.

If you do have symptoms, your doctor will likely recommend a combination of surgery and medication to help manage any symptoms you may have.

Surgery

Surgery is the main treatment for diaphragmatic endometriosis.

Surgery can be done in a few different ways:

  • Laparotomy. In this procedure, your surgeon makes a large cut through the wall of the upper abdomen and then removes parts of the diaphragm affected by endometriosis. In , this treatment reduced symptoms in all women and completely relieved chest and shoulder pain in seven out of eight women.
  • Thoracoscopy. For this procedure, your surgeon inserts a flexible scope and small instruments through small incisions in the chest to view and possibly remove areas of endometriosis within the diaphragm.
  • Laparoscopy. In this procedure, your surgeon inserts a flexible scope and small instruments into the abdomen to remove areas of endometriosis within the abdomen and pelvis.

Your surgeon can also use a laser to treat tissue affected by endometriosis. Surgery may also be necessary to manage scar tissue formation, a common complication in endometriosis. New treatment approaches are often becoming available. Talk to your doctor.

If the endometriosis is in both your diaphragm and pelvis, you might need more than one surgery.

Medication

Two types of medicines are currently used to treat endometriosis: hormones and pain relievers.

Hormone therapy can slow the growth of endometrial tissue and lower its activity outside of the uterus.

Hormonal treatments include:

  • birth control, including pills, patch, or ring
  • gonadotropin-releasing hormone (GnRH) agonists
  • danazol (Danocrine), now less commonly used
  • progestin injections (Depo-Provera)

Your doctor may also recommend over-the-counter (OTC) or prescription nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen (Advil) or naproxen (Aleve), to control pain.

Rarely, endometriosis of the diaphragm can cause holes to form in the diaphragm.

This can lead to life-threatening complications such as:

  • collapsed lung (pneumothorax) during your period
  • endometriosis in the chest wall or lungs
  • air and blood in the chest cavity

Having surgery to remove endometriosis within the diaphragm may reduce your risk of these complications.

Endometriosis of your diaphragm shouldn’t affect your fertility. But many women with this form of endometriosis also have it in their ovaries and other pelvic organs, which can cause fertility problems. Surgery and in vitro fertilization can increase your odds of getting pregnant.

Your outlook depends on how severe your endometriosis is, and how it’s treated.

This type of endometriosis may not cause symptoms. If it’s painful or causes complications, you can have surgery to remove the endometrial tissue.

Endometriosis is a chronic condition, and it can have a big impact on your day-to-day life. To find support in your area, visit the or the .