The endometrium is the tissue that lines the uterus. During each menstrual cycle, a new lining grows, getting ready for a possible pregnancy. If you don't become pregnant during that cycle, the lining sheds. This is your menstrual period.

Endometriosis (say "en-doh-mee-tree-OH-sus") is the growth of this tissue outside of the uterus, usually on the ovaries or the fallopian tubes. It also may grow on the outside surface of the uterus, the bowels, or other organs in the belly.

These growths are called "implants." They grow, bleed, and break down with each menstrual cycle, just like the lining of the uterus does. This can cause pain and can make it hard to get pregnant.

In some cases, scar tissue forms around implants. This also can cause pain and trouble getting pregnant.

The female hormone estrogen makes the implants grow. Because the ovaries make most of your body's estrogen, taking out the ovaries can relieve your symptoms.

While some women never have symptoms, others have severe pain that can make it hard to enjoy daily activities. In some cases, the problem can affect how well your bowels, bladder, or other organs work.

Pain from implants may be mild for a few days before your menstrual period. It may get better during your period. But if an implant grows in a sensitive area such as the rectum, it can cause constant pain or pain during sex, exercise, or bowel movements.

Symptoms often get better during pregnancy and usually go away after menopause.

This surgery works very well to relieve pain from endometriosis. But pain does return for up to 15 out of 100 women who have surgery.^{footnote 1} This means that in 85 out of 100 women who have surgery, the pain doesn't come back.

Taking out the uterus and ovaries is usually the last choice in treatment. This is because:

• It is a major surgery with a long recovery.
• It makes you unable to get pregnant.
• It causes a sudden drop in your level of estrogen. This leads to menopause and side effects such as making your bones thinner.

You can take low-dose estrogen after surgery to protect your bones and prevent symptoms of menopause. But this increases the chance that implants could come back.^{footnote 1}

This surgery has different types of risks.

Risks from having surgery

Most women don't have problems from surgery. But problems can include:

• A fever. A slight fever is common after any surgery.
• Trouble urinating.
• Continued heavy bleeding. Some vaginal bleeding within 4 to 6 weeks after surgery is normal.
• Continued pain. Pelvic pain that you had before surgery may not be helped by surgery.
• Change in sexual function.
• Infection.
• Rare problems, such as:
  • Blood clots in the legs or the lungs.
  • Scar tissue (also called adhesions).
  • Injury to other organs, such as the bladder or bowel.
  • A collection of blood at the surgical site.
  • Problems from general anesthesia.
  • Severe blood loss that causes you to need more blood (transfusion).

Risks from not having ovaries

Without estrogen, you can have severe symptoms of menopause, such as hot flashes, vaginal dryness, moodiness, and depression. Your bones also begin to thin. This increases your risk of osteoporosis in later life. Taking estrogen can prevent these problems.

If you don't want to take estrogen, you can take another type of medicine to make your bones stronger.

Risks from taking estrogen

Estrogen therapy (ET) may increase the risk of health problems in a small number of women. A woman's increase in risk depends on her age, her personal risk, and when she starts ET. Some of the problems include:^{footnote 2}

• Stroke.
• Blood clots.
• Gallstones.
• Dementia.
• Urinary incontinence.

Your doctor might suggest surgery if:

• You have severe symptoms.
• You're not close to menopause.
• You don't plan to get pregnant.
• You tried hormones or had laparoscopic surgery to remove tissue, but your symptoms are still bad.