Differences Between Endometriosis and Adenomyosis

Medically Reviewed by Traci C. Johnson, MD on September 02, 2022
4 min read

Few women may know what the endometrium is. But they all probably have seen it. It’s the tissue inside the uterus that your body peels off and sheds during your menstrual periods.

When tissue similar to the lining of the uterus grows in places it shouldn’t, you can have similar but separate conditions called endometriosis and adenomyosis. They affect different parts of your body, share some symptoms, and may require different treatments.

You can have both of these problems at the same time. Doctors don’t know exactly what causes them.

In endometriosis, the same type of cells that line the uterus, or womb, also grows outside of it. The growth can breach nearby organs like your ovaries, fallopian tubes, and bladder. It can make it hard for you to get pregnant.

Adenomyosis, on the other hand, happens when the same kind of cells that line the uterus also grows deep in the muscular wall of the uterus and thickens it." It doesn’t go past the uterus itself. 

Even when the uterine lining grows where it doesn’t belong, it still carries on as usual. It gets thicker and thicker as your monthly cycle nears and then bleeds when your hormones signal that you’re not pregnant. That causes problems.

With endometriosis, it irritates and swells nearby tissues and can lead to scarring. You may notice:

  • Belly pain. This is the most common symptom. It may be worse around the time of your period.
  • Pain in your back or leg, or pain during or after sex
  • Heavy or painful menstrual bleeding
  • Pain while you pee or poop
  • Nausea, vomiting, or feeling tired

With adenomyosis, the inside of your womb gets thicker and bigger, which doesn’t usually happen with endometriosis. The enlarged uterus may:

  • Put pressure on your bladder and rectum
  • Change the way your uterine muscles tighten (contract)
  • Cause heavy and painful periods

Both conditions can lead to anemia from menstrual bleeding. This means you don’t have enough iron in your blood. Iron supplements may help.

Doctors don’t know what causes either endometriosis or adenomyosis. But some things can make them more likely to happen.

Your chances for endometriosis go up if:

  • You’re in your 30s or 40s.
  • Your mother, sister, or daughter has it.
  • You have heavy periods that last more than 7 days.
  • Your periods are less than 27 days apart.
  • You started your period before you were 11 years old.

Your risk of adenomyosis goes up if you:

  • Are in your 40s or older; women diagnosed with adenomyosis tend to be older than those who have endometriosis.
  • Have given birth at least once
  • Started your periods at age 10 or younger
  • Have menstrual cycles that last 24 days or less

It can be hard to tell if you have endometriosis or adenomyosis, or both, or something else like fibroids or cysts. Pelvic pain can be caused by many other conditions, including pelvic floor muscle spasm, pelvic infections, and irritable bowel syndrome.

Endometriosis. Sometimes ultrasound can show endometriosis. An MRI also can show larger areas of endometrial tissue outside the uterus, but it could miss smaller patches. The only way to know for sure you have it is with surgery. That way, your doctor can look for endometrial tissue in your belly (outside your uterus). If they see any, small pieces can be taken out for a lab test to confirm the diagnosis.

Adenomyosis. Your uterus may feel bigger than normal and be tender when you push on your belly. An ultrasound or an MRI might diagnose adenomyosis. Sometimes you might not know you have until after a hysterectomy, when your uterine tissue is tested in a lab.

Endometriosis and adenomyosis usually don’t require treatment unless they cause you problems.

Both may be managed with pain medicines, like non-steroidal anti-inflammatory drugs (NSAIDs).

Hormone medicines, such as birth control pills, progestin and progesterone, and gonadotropin-releasing hormone agonists might also be used. These control the way your hormones cycle and can help slow the growth of the endometrial tissue, no matter where it is, but they don’t make it go away. With endometriosis, hormone medicines may help keep new scar tissue from forming.

Gonadotropin-releasing hormone (GnRH) receptor antagonists are another class of hormonal treatments that can be used to treat endometriosis pain. Elagolix (Orilissa) is the only GnRH receptor antagonist approved for pain, but other drugs are being used off-label to treat endometriosis. Thy include cetrorelix (Cetrotide) and ganirelix acetate (Antagon).

Several treatments may help control the heavy bleeding from adenomyosis. A special kind of IUD, a birth control device, is one option. Others include a procedure to block the supply of blood to the uterus (uterine artery embolization) or surgery to scar the uterine lining to make your periods lighter (endometrial ablation).

But the only sure cure is a hysterectomy to remove your uterus. You have to be sure you don't want anymore pregnancies before you decide to have a hysterectomy, embolization, or ablation.

For endometriosis, surgery might be an option. It can take out the tissue that’s outside your uterus. Scar tissue can be removed, too. If you don’t plan to have more children, your uterus, fallopian tubes, and ovaries can be taken out in a surgery called a hysterectomy with bilateral salpingo-oophorectomy. But even after surgery, there’s a small chance that the pain will come back.