Both endometriosis and fibroids affect the uterus and may cause similar symptoms and complications. Proper diagnosis and treatment can reduce the risk of long-term health issues.

The uterus is the center of the female reproductive system. Like any organ, it can develop medical conditions. Two conditions that affect the uterus are endometriosis and fibroids. They have similar symptoms, such as pain and heavy periods, which can make them hard to tell apart. It’s important to know the difference, though, as they have different causes and treatments.

Here’s what you need to know about endometriosis and fibroids, as well as how these conditions are diagnosed and treated.

“Endometrium” is the medical term for the lining of the uterus. Endometriosis is a chronic condition that happens when endometrial-like tissue grows outside the uterus in other parts of the body – the ovaries, fallopian tubes, or the surface of the uterus. This tissue may also grow on the cervix, bowel, bladder, or other nearby structures as well. Rarely, some people may have endometrial tissue that grows farther away and impacts the lungs, brain, or skin.

No matter where it ends up, this tissue can swell and bleed, much like the lining inside the uterus does during menstruation. The pain from endometriosis results from the tissue growing and bleeding in areas of the body where it cannot be shed, like in the uterus.

Fibroids are noncancerous growths that form inside or around the uterus. You may see them referred to as “leiomyoma” or “myoma” on medical paperwork. A person can have just one fibroid or many fibroids. These growths can range in size from as small as a seed to as large as a grapefruit.

While some fibroids cause no symptoms, others can lead to heavy periods, pelvic pain, or pressure on other organs.

Endometriosis and fibroids can cause symptoms ranging from uncomfortable to painful. The type of symptoms, timing, and location of the pain often give doctors clues about which condition is more likely.

Symptoms shared by endometriosis and fibroids:

Endometriosis causes pain that can start before a period and last during or even after it ends. The pain may also show up in the lower back, or during bowel movements or urination, especially during menstruation. People with endometriosis may also experience digestive issues, like diarrhea, constipation, or nausea.

Fibroids, on the other hand, are more likely to cause pressure or a feeling of fullness in the lower belly. If the fibroids are large, they might cause bloating or make it hard to go to the bathroom. Some people may also notice that their stomach looks swollen.

You’ll notice the language used to share stats and other data points is pretty binary, fluctuating between the use of “male” and “female” or “men” and “women.” While we typically avoid language like this, specificity is key when reporting on research participants and clinical findings.

Endometriosis affects up to 11% of womenages 15 years to 44 years old and is most common in women between the ages of 30 years and 40 years.

Other risk factors include:

  • having a family history of endometriosis
  • having periods that last a week or longer
  • having short menstrual cycles (27 days or fewer)
  • not having gone through pregnancy/childbirth

Fibroids are most commonly found in middle-aged women before menopause. Experts explain that between 20% to 80% of women will develop fibroids before age 50.

Other risk factors include:

  • having a family history of fibroids
  • being Black or African-American
  • having obesity or overweight
  • eating lots of red meat and ham

What is the autoimmune connection between endometriosis vs fibroids?

Endometriosis is not classified as an autoimmune disorder. That said, research suggests that people with endometriosis may have a higher risk of developing autoimmune and autoinflammatory disorders, like arthritis, rheumatoid arthritis, multiple sclerosis, celiac disease, and psoriasis.

There is currently no evidence that fibroids are related to autoimmune issues.

Your primary care doctor may suggest you see a gynecologist who specializes in the uterus and other female reproductive organs.

Your appointment will involve taking a health history (including family history), sharing your symptoms, and having a pelvic exam. Based on your symptoms and your doctor’s findings, any further testing will be determined.

Endometriosis can be difficult to diagnose because the tissue may or may not show up on standard imaging tests, like ultrasound or magnetic resonance imaging (MRI). To confirm the diagnosis, your doctor may perform a laparoscopy. This minor surgery lets the doctor look inside the body with a small camera and take a tissue sample, if necessary.

Fibroids may be easier to detect because they grow in or on the uterus and can usually be seen with imaging tests, including:

Endometriosis and fibroids are treated on a case-by-case basis depending on symptom severity, a person’s age, and whether or not a person wants to preserve fertility.

Treatments these conditions have in common include:

  • over-the-counter (OTC) medication for pain, like ibuprofen, to manage discomfort
  • hormone therapy, like birth control pills, to control symptoms and reduce bleeding
  • surgery (to remove the tissue/growths) or a hysterectomy (to remove the uterus in severe cases)

Specific treatment for endometriosis involves lowering estrogen levels to slow the growth of endometrial tissue. Your doctor may suggest taking hormonal medications for long-term management. In some cases, a laparoscopy can remove or burn away the tissue to relieve pain.

Fibroids only need to be addressed if they are causing issues. Treatment involves procedures that shrink or remove the fibroids:

There is no cure for endometriosis. This condition can make it harder to get pregnant and may increase the risk of miscarriage or ectopic pregnancy. In about one-third of cases, the condition may improve on its own without treatment. However, studies show that pain can come back in between 17% to 34% of people after stopping treatment.

Fibroids may cause unpleasant symptoms, but they are most often benign. These fibroids only cause infertility in 1% to 2% of individuals who have them, and rarely affect pregnancy. Fibroids that do cause more complications grow slowly and often respond well to treatment.

Make an appointment with your doctor if you have pain, bleeding, or other health issues that concern you. While having endometriosis or fibroids may significantly impact your quality of life, you don’t have to navigate the symptoms alone. Getting an accurate diagnosis is the first step toward finding the right treatment and protecting your reproductive health.