Endometriosis is a painful, chronic disease that stems from the uterus and can impact the entire body. According to the Endometriosis Foundation of America, this medical condition affects around 10 percent of women in the United States. Doctors aren’t exactly sure what causes endometriosis or how to cure it.

Endometriosis often gets misdiagnosed or overlooked, as symptoms can be confused with pelvic inflammatory disease (PID), irritable bowel syndrome (IBS), fibromyalgia, and other illnesses. Diagnosis may be further complicated by the presence of multiple chronic conditions. However, with an accurate diagnosis, treatment can improve your health and quality of life.

What Are the Main Causes of Endometriosis?

The endometrium is the lining of the uterus. Every month, it builds up, breaks down, and sheds during the menstrual period. Endometriosis happens when tissue similar to endometrial tissue grows outside of the uterus.

When endometrial tissue exists outside the uterus, implants (also known as growths or lesions) form. This tissue responds to the menstrual cycle. Like the lining of the uterus, endometrial growths are affected by the hormonal changes associated with menstruation.

Health care experts haven’t definitively proven what causes endometriosis, but some of their theories include:

• A backup of menstrual flow — Menstrual blood may go the “wrong way” back into the pelvic cavity, carrying endometrial cells to the pelvic wall and other organs.
• Complications from surgery — Endometrial cells might attach to scars in the stomach area after a C-section or other surgery.
• Cell transport — Endometrial cells may travel to other areas through the bloodstream or lymphatic system.
• Hormonal effects on embryonic or peritoneal cells — Estrogen may turn new cells or cells in the abdomen into endometrial tissue during puberty.
• Immune system dysfunction — An underlying problem with the immune system may prevent the body from stopping the overgrowth of endometrial tissue.

Some known risk factors that increase a person’s chances of developing endometriosis include having:

• A family history of endometriosis, particularly in first-degree relatives (e.g., parents or siblings)
• Heavy periods that last for seven days or longer
• High levels of estrogen
• Low body mass index (BMI)
• Later-than-average menopause
• Shorter menstrual cycles (fewer than 21 days)

Sharing the details of your medical and menstrual history with your health care provider can help them determine if you have endometriosis.

Where Can Endometriosis Occur?

Endometriosis can occur in many places inside the body, but most commonly in the pelvic cavity. Endometriosis most commonly involves the:

• Ovaries
• Fallopian tubes
• Ligaments that support the uterus
• Spaces around the reproductive organs
• Tissue lining the pelvic cavity

Endometrial tissue may also spread to nearby organs such as the bladder or bowel. Endometriosis has also been found in distant organs such as the nasal cavity, lungs, or the skin.

Endometriosis in the Past and Present

Throughout history, the symptoms of severe, chronic pelvic pain were often attributed to mental illness, demonic possession, or promiscuity. Hysteria, which means “of the womb” in Greek, was a common diagnosis for many women who complained of pelvic pain. Pregnancy was considered a cure for dysmenorrhea (painful periods), and women with this complaint were typically encouraged to marry and get pregnant as soon as possible. Modern medical science has thoroughly disproven these theories.

In the 1920s, Canadian gynecologist Thomas Cullen first identified and described how endometrial implants are associated with disease activity. In the 1940s, new techniques in endoscopy allowed doctors to better examine and visualize what was happening inside the body in cases of endometriosis. The first birth control pill became available in 1960, and the age of hormonal treatment for endometriosis began. Endometriosis treatment continued improving in the 1970s, with laparoscopic surgery that enabled surgeons to remove implants and adhesions in a less invasive way than traditional surgery.

How Common Is Endometriosis Today?

According to Johns Hopkins Medicine, between 2 percent to 10 percent of women in the U.S. have endometriosis. Globally, it affects about 200 million women, according to the Endometriosis Foundation of America. However, it’s impossible to know how many people remain undiagnosed. Endometriosis mostly affects individuals in their reproductive years, especially between the ages of 25 and 40, but it can develop in children as young as 11. Endometriosis affects people of all ethnic and racial backgrounds equally.

What Are the Symptoms of Endometriosis?

Endometriosis can be particularly disruptive during your period (menstrual cycle). Some cramping during periods is normal, regardless of whether you have endometriosis. However, endometriosis can cause severe cramping that prevents you from doing your usual activities. People with endometriosis also commonly experience pain during sex.

Other symptoms of endometriosis may include:

• Back pain
• Heavy menstrual flow
• Chronic fatigue
• Painful bowel movements or urination

Endometriosis can also cause bloating and gastrointestinal issues like nausea, diarrhea, and constipation.

What Happens if Someone Has Endometriosis?

Endometriosis affects the body’s hormones, immune system, digestive system, and fertility. Up to 50 percent of people with endometriosis have trouble getting pregnant. As a result, it can lead to significant social impacts on work, education, and relationships.

What Are the Stages of Endometriosis?

There are four stages of endometriosis:

• Stage 1 — Minimal
• Stage 2 — Mild
• Stage 3 — Moderate
• Stage 4 — Severe

The stage is determined by the location, amount, depth, and size of the endometrial implants.

The stage isn’t just about the level of pain. In other words, someone with stage 1 endometriosis may experience significantly more pain than someone with stage 4 disease.

How Is Endometriosis Diagnosed?

Typically, a gynecologist or other health care provider will review your medical history and complete a physical examination and pelvic exam. Endometriosis can only be definitively diagnosed through laparoscopy, a minor surgery to look inside the abdomen. During this procedure, a doctor may perform a biopsy, taking a tissue sample to examine under a microscope and confirm the condition.

Doctors may also use imaging tests like ultrasounds, computed tomography (CT) scans, and magnetic resonance imaging (MRI) scans to see if you have endometriosis. However, laparoscopy is considered the gold standard for diagnosing endometriosis.

How Is Endometriosis Treated?

While there’s no cure for endometriosis, there are several ways to help manage its symptoms. Your health care provider can help you decide on the best treatment options based on your situation, such as whether you want to get pregnant and how much endometriosis affects your daily life.

Treatments may include:

• Pain medications (over-the-counter or prescription)
• Hormonal therapy (oral contraceptives or injections)
• Surgery (laparoscopy, laparotomy, or hysterectomy)

Noninvasive treatments, like birth control pills, are usually recommended before surgery. However, people who are having fertility issues or severe symptoms may benefit more from having a procedure to remove endometriosis patches.

Can You Get Pregnant With Endometriosis?

It is possible to get pregnant with endometriosis, but if you have endometriosis, you may find it harder to conceive. Researchers think endometriosis impacts as many as half of infertility cases.

There are several possible causes of this infertility:

• Endometrial growths may block or alter the shape of the pelvis and reproductive organs, making it harder for sperm cells to reach the ovum (egg).
• The immune system, which normally helps defend the body against disease, may attack the embryo.
• The endometrium does not develop as it should, making it difficult for an embryo to implant in the womb.

Additionally, some treatments for endometriosis may delay or prevent pregnancy.

Connections Between Endometriosis and Cancer

Some research suggests that endometriosis may raise the risk of ovarian cancer and of another form of cancer called endometriosis-associated adenocarcinoma. However, the risk of both of these cancers is still low, even if you have endometriosis. Keeping up with your recommended cancer screenings and health care visits can help prevent other health problems and catch any issues early.

Talk to Others Who Understand

MyEndometriosisTeam is the social network for people with endometriosis. More than 136,000 members come together to ask questions, give advice, and share their stories with others who understand life with endometriosis.

Do you have endometriosis? What challenges have you encountered during diagnosis and treatment? Share your experience in the comments below or start a conversation by posting on your Activities page.