Endometriosis and adenomyosis

What it is

Endometriosis is a long-term condition in which tissue similar to the lining of the uterus grows outside the uterus. It affects about 1 in 10 women of reproductive age, an estimated 190 million worldwide.^1,2

The patches, called lesions, are usually inside the pelvis: on the ovaries, the fallopian tubes, the outside of the uterus, the bladder, the bowel, or the space behind the uterus. Rarely they're found farther away, such as on the diaphragm.¹ They respond to estrogen like the uterine lining does, so they can grow and bleed each month. That causes inflammation, swelling and scar tissue called adhesions, which can make organs stick together.¹

The signs

The most common symptom is long-lasting pelvic pain. Others include:¹

• period pain that often gets worse over time
• pain during sex
• pain when peeing or pooping
• constipation, bloating and other gut problems
• trouble getting pregnant

Some people have no symptoms and find out only when they can't get pregnant or during surgery for something else.¹ Among women with infertility, 25 to 50% have endometriosis.² It can run in families.¹

How much it hurts doesn't show how much is there. Someone can have severe pain and a few small lesions, or little pain and many lesions.¹

Why it takes so long to diagnose

On average it takes 4 to 12 years to get a diagnosis.² In a 2026 study of about 6,950 people in France, the average was 10 years for endometriosis and 11 for adenomyosis, and every extra health professional seen before diagnosis added time.³ Part of the reason is that its symptoms look like other problems, such as irritable bowel syndrome or urinary problems, which a doctor needs to rule out.¹

One story: Her symptoms started at 12. Doctors told her the pain was normal for her, and she was diagnosed at 32, after researching endometriosis herself.

Myth: You need surgery before you can be diagnosed or treated for endometriosis.

For a long time this was the standard advice, so many of us heard it from doctors. Guidance has changed. ACOG now says the best first test is a transvaginal ultrasound, sometimes followed by an MRI, and that treatment for symptoms can start right away, even before imaging.¹ Surgery, called laparoscopy, is still the only way to confirm endometriosis for certain, but it isn't required.¹

A normal scan doesn't rule it out. Some lesions are hard to see on imaging, so someone can still have endometriosis after a clear ultrasound.¹ If symptoms continue, it's reasonable to keep asking.

One story: Her bloodwork, exams, ultrasound and MRI were all normal. Along the way she was told she had IBS, fibromyalgia and health anxiety. Ten years after her symptoms began, surgery found deep endometriosis.

Adenomyosis

In adenomyosis, tissue like the uterine lining grows into the muscle wall of the uterus instead of outside it. The wall thickens and the uterus can get bigger.⁴ Its main signs are heavy periods and painful periods, and pelvic pain, pain during sex and bloating can come too. About 1 in 3 people with it have no symptoms.⁴

It is most often found in people aged 40 to 50 who have given birth, but doctors are finding it more often in people in their 30s, and about 2 to 5% of teens with severe period pain have it.⁴ It is usually found with a transvaginal ultrasound or an MRI.⁴

Both conditions usually ease after menopause, when the ovaries stop making estrogen.^1,4

Treatment

There is no cure for endometriosis, but there are many ways to manage it, including medicines, surgery or both, and the right plan depends on symptoms and whether someone wants to get pregnant.^1,2 See ACOG's guide to endometriosis for the options.

What to track and ask

Before a visit, write down for a few cycles: where the pain is, when it starts and stops in the cycle, whether peeing, pooping or sex hurts, how it affects school, work or sleep, what you've tried for it, and whether anyone in your family has endometriosis.

Questions to ask:

• Could this be endometriosis or adenomyosis? What else could it be?
• Should I have a transvaginal ultrasound? If it's normal, what's next?
• Can I start treatment for the pain now?

When to see a doctor

See a doctor if period pain keeps you from your normal activities, gets worse over time, or isn't eased by pain relievers like ibuprofen.⁵