What Is Endometriosis?

Endometriosis is a long-term (chronic) condition in which tissue similar to the lining of the uterus grows outside the uterus. These growths are most often found on the ovaries, the fallopian tubes, the outer surface of the uterus, the ligaments that support the uterus, and the lining of the pelvis. Less often, they involve the bowel or bladder.

The World Health Organization estimates that endometriosis affects roughly 10% of women and girls of reproductive age worldwide, which works out to about 190 million people. Even so, many people live with symptoms for years before they get a diagnosis. Painful periods are often dismissed as "normal," and the symptoms overlap with several other conditions.

Like the uterine lining, endometriosis tissue responds to the hormonal changes of the menstrual cycle. It can become inflamed and bleed, but unlike a normal period, that blood and tissue has no way to leave the body. Over time this can cause inflammation, scar tissue (adhesions), and fluid-filled cysts on the ovaries called endometriomas.

What Causes It?

No single cause has been proven. Researchers think several factors probably work together:

  • Retrograde menstruation: some menstrual blood flows backward through the fallopian tubes into the pelvis instead of leaving the body. This happens in many people, so on its own it does not explain who develops endometriosis.
  • Immune system factors: the immune system may fail to clear misplaced tissue.
  • Genetics: having a mother or sister with endometriosis raises your risk.
  • Hormones: estrogen fuels the growth of endometriosis tissue.
  • Cell changes: some cells outside the uterus may transform into endometrium-like cells.

Endometriosis is not caused by anything a person did, and it is not a sexually transmitted infection.

Common Symptoms

Symptoms vary widely. Some people with extensive disease have little pain, while others with small lesions have severe pain. The most common symptoms include:

  • Painful periods (dysmenorrhea) that get worse over time or do not respond to over-the-counter pain relievers
  • Chronic pelvic or lower back pain, including between periods
  • Pain during or after sex (dyspareunia), especially with deep penetration
  • Painful bowel movements or urination, often worse during a period
  • Heavy or irregular bleeding in some people
  • Bloating, nausea, and fatigue
  • Difficulty getting pregnant

Because bowel symptoms such as bloating and cramping are common, endometriosis is sometimes mistaken for irritable bowel syndrome. Keeping a symptom diary that tracks pain, bleeding, and bowel or bladder changes across your cycle can help your clinician see the pattern.

How Endometriosis Is Diagnosed

There is no simple blood test for endometriosis. Diagnosis usually involves several steps:

  1. Medical history: your clinician will ask about your periods, pain, sexual health, bowel and bladder symptoms, and family history.
  2. Pelvic exam: tender areas, nodules, or a fixed (less mobile) uterus can be clues, although the exam is often normal.
  3. Imaging: a transvaginal ultrasound can identify endometriomas and, in experienced hands, some deep endometriosis. MRI may be used to map deeper disease before surgery.
  4. Laparoscopy: a minimally invasive surgery in which a camera is passed through a small incision near the navel. The surgeon can see lesions directly and take a biopsy, and can often remove lesions during the same procedure.

Laparoscopy has long been considered the way to confirm the diagnosis. More recent guidelines, including the 2022 European Society of Human Reproduction and Embryology (ESHRE) guideline, support starting treatment based on symptoms and imaging without requiring surgery first. If your symptoms strongly suggest endometriosis, you do not always need an operation before trying treatment.

Treatment Options

Endometriosis cannot currently be cured, but symptoms can usually be managed. The right plan depends on how severe your symptoms are, your age, and whether you want to become pregnant soon.

Pain relief: nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen or naproxen are often the first step for period pain. Taking them a day before your period is expected can work better than waiting until pain peaks.

Hormonal treatments: because estrogen drives endometriosis, many treatments lower estrogen or block its effects on the tissue:

  • Combined hormonal contraceptives (pill, patch, or ring), sometimes taken continuously to skip periods
  • Progestin-only options, such as progestin pills, the hormonal IUD, the contraceptive implant, or the injection
  • GnRH antagonists (such as elagolix, or relugolix in a combination pill), which lower estrogen levels
  • GnRH agonists (such as leuprolide), which create a temporary low-estrogen state and are usually paired with "add-back" hormone therapy to protect bone and reduce side effects

Hormonal treatments can reduce pain but do not permanently remove lesions, and symptoms often return when they are stopped. Several of these medicines prevent pregnancy, so they are not used while trying to conceive.

Surgery: laparoscopic surgery can remove (excise) or destroy (ablate) lesions, cut through adhesions, and remove endometriomas. Surgery can relieve pain, but lesions can come back over time. Hysterectomy, sometimes with removal of the ovaries, may be considered for severe pain when other options have failed and future pregnancy is not wanted. Even hysterectomy does not guarantee that pain will stop, so it is a decision to make carefully with a specialist.

Supportive care: pelvic floor physical therapy, heat, regular exercise, and treatment for related problems such as anxiety, depression, or poor sleep can all help with chronic pain. Many people do best with a combination of approaches rather than a single treatment.

Endometriosis and Fertility

Endometriosis is common among people who have trouble getting pregnant, but many people with endometriosis conceive without treatment. Inflammation, adhesions that distort the tubes and ovaries, and endometriomas can all make conception harder.

If you have endometriosis and want to get pregnant, talk with your clinician early. Depending on your age and situation, options may include surgery to remove lesions, ovulation induction with intrauterine insemination (IUI), or in vitro fertilization (IVF). People who want to delay pregnancy may ask about egg freezing, especially before surgery on the ovaries, because removing endometriomas can reduce the number of eggs available.

Endometriosis vs. Adenomyosis

Adenomyosis is a related but separate condition. In adenomyosis, endometrial-like tissue grows into the muscular wall of the uterus rather than outside it. It typically causes heavy, painful periods and an enlarged, tender uterus. The two conditions can occur together, and some treatments overlap, but adenomyosis is usually seen on ultrasound or MRI rather than at laparoscopy.

When to See a Doctor

Book an appointment if:

  • Period pain keeps you from school, work, or normal activities
  • Over-the-counter pain relievers no longer help
  • You have pain during sex, or pain with bowel movements or urination around your period
  • You have been trying to get pregnant for 12 months (or 6 months if you are 35 or older)

Seek urgent care for sudden, severe pelvic pain, especially with fever, vomiting, or fainting. These can be signs of an emergency such as a ruptured or twisted ovarian cyst.

Frequently Asked Questions

Does endometriosis go away after menopause? Symptoms often improve after menopause because estrogen levels fall, but not always, particularly for people who take hormone therapy.

Is endometriosis a type of cancer? No. Endometriosis is not cancer. Studies show a small increase in the risk of certain types of ovarian cancer in people with endometriosis, but the overall risk remains low.

Can teenagers have endometriosis? Yes. Symptoms can start with the first periods. Severe period pain in teens deserves evaluation rather than being written off as normal.

Will pregnancy cure endometriosis? No. Some people feel better during pregnancy, but symptoms commonly return afterward.

This article is for informational purposes only and is not a substitute for professional medical advice. Always consult a healthcare provider about your symptoms and treatment options.