Endometriosis (en-doe-me-tree-O-sis) is an often painful disorder in which tissue similar to the tissue that normally lines the inside of your uterus — the endometrium — grows outside your uterus. Endometriosis most commonly involves your ovaries, fallopian tubes and the tissue lining your pelvis. Rarely, endometrial-like tissue may be found beyond the area where pelvic organs are located.

With endometriosis, the endometrial-like tissue acts as endometrial tissue would — it thickens, breaks down and bleeds with each menstrual cycle. But because this tissue has no way to exit your body, it becomes trapped. When endometriosis involves the ovaries, cysts called endometriomas may form. Surrounding tissue can become irritated, eventually developing scar tissue and adhesions — bands of fibrous tissue that can cause pelvic tissues and organs to stick to each other.

Endometriosis can cause pain — sometimes severe — especially during menstrual periods. Fertility problems also may develop. Fortunately, effective treatments are available.

The primary symptom of endometriosis is pelvic pain, often associated with menstrual periods. Although many experience cramping during their menstrual periods, those with endometriosis typically describe menstrual pain that's far worse than usual. Pain also may increase over time.

Common signs and symptoms of endometriosis include:

• Painful periods (dysmenorrhea). Pelvic pain and cramping may begin before and extend several days into a menstrual period. You may also have lower back and abdominal pain.
• Pain with intercourse. Pain during or after sex is common with endometriosis.
• Pain with bowel movements or urination. You're most likely to experience these symptoms during a menstrual period.
• Excessive bleeding. You may experience occasional heavy menstrual periods or bleeding between periods (intermenstrual bleeding).
• Infertility. Sometimes, endometriosis is first diagnosed in those seeking treatment for infertility.
• Other signs and symptoms. You may experience fatigue, diarrhea, constipation, bloating or nausea, especially during menstrual periods.

The severity of your pain may not be a reliable indicator of the extent of your condition. You could have mild endometriosis with severe pain, or you could have advanced endometriosis with little or no pain.

Endometriosis is sometimes mistaken for other conditions that can cause pelvic pain, such as pelvic inflammatory disease (PID) or ovarian cysts. It may be confused with irritable bowel syndrome (IBS), a condition that causes bouts of diarrhea, constipation and abdominal cramping. IBS can accompany endometriosis, which can complicate the diagnosis.

When to see a doctor

See your doctor if you have signs and symptoms that may indicate endometriosis.

Endometriosis can be a challenging condition to manage. An early diagnosis, a multidisciplinary medical team and an understanding of your diagnosis may result in better management of your symptoms.

Although the exact cause of endometriosis is not certain, possible explanations include:

• Retrograde menstruation. In retrograde menstruation, menstrual blood containing endometrial cells flows back through the fallopian tubes and into the pelvic cavity instead of out of the body. These endometrial cells stick to the pelvic walls and surfaces of pelvic organs, where they grow and continue to thicken and bleed over the course of each menstrual cycle.
• Transformation of peritoneal cells. In what's known as the "induction theory," experts propose that hormones or immune factors promote transformation of peritoneal cells — cells that line the inner side of your abdomen — into endometrial-like cells.
• Embryonic cell transformation. Hormones such as estrogen may transform embryonic cells — cells in the earliest stages of development — into endometrial-like cell implants during puberty.
• Surgical scar implantation. After a surgery, such as a hysterectomy or C-section, endometrial cells may attach to a surgical incision.
• Endometrial cell transport. The blood vessels or tissue fluid (lymphatic) system may transport endometrial cells to other parts of the body.
• Immune system disorder. A problem with the immune system may make the body unable to recognize and destroy endometrial-like tissue that's growing outside the uterus.

Several factors place you at greater risk of developing endometriosis, such as:

• Never giving birth
• Starting your period at an early age
• Going through menopause at an older age
• Short menstrual cycles — for instance, less than 27 days
• Heavy menstrual periods that last longer than seven days
• Having higher levels of estrogen in your body or a greater lifetime exposure to estrogen your body produces
• Low body mass index
• One or more relatives (mother, aunt or sister) with endometriosis
• Any medical condition that prevents the passage of blood from the body during menstrual periods
• Disorders of the reproductive tract

Endometriosis usually develops several years after the onset of menstruation (menarche). Signs and symptoms of endometriosis may temporarily improve with pregnancy and may go away completely with menopause, unless you're taking estrogen.

Infertility

The main complication of endometriosis is impaired fertility. Approximately one-third to one-half of women with endometriosis have difficulty getting pregnant.

For pregnancy to occur, an egg must be released from an ovary, travel through the neighboring fallopian tube, become fertilized by a sperm cell and attach itself to the uterine wall to begin development. Endometriosis may obstruct the tube and keep the egg and sperm from uniting. But the condition also seems to affect fertility in less-direct ways, such as by damaging the sperm or egg.

Even so, many with mild to moderate endometriosis can still conceive and carry a pregnancy to term. Doctors sometimes advise those with endometriosis not to delay having children because the condition may worsen with time.

Cancer

Ovarian cancer does occur at higher than expected rates in those with endometriosis. But the overall lifetime risk of ovarian cancer is low to begin with. Some studies suggest that endometriosis increases that risk, but it's still relatively low. Although rare, another type of cancer — endometriosis-associated adenocarcinoma — can develop later in life in those who have had endometriosis.

To diagnose endometriosis and other conditions that can cause pelvic pain, your doctor will ask you to describe your symptoms, including the location of your pain and when it occurs.

Tests to check for physical clues of endometriosis include:

• Pelvic exam. During a pelvic exam, your doctor manually feels (palpates) areas in your pelvis for abnormalities, such as cysts on your reproductive organs or scars behind your uterus. Often it's not possible to feel small areas of endometriosis unless they've caused a cyst to form.
• Ultrasound. This test uses high-frequency sound waves to create images of the inside of your body. To capture the images, a device called a transducer is either pressed against your abdomen or inserted into your vagina (transvaginal ultrasound). Both types of ultrasound may be done to get the best view of the reproductive organs. A standard ultrasound imaging test won't definitively tell your doctor whether you have endometriosis, but it can identify cysts associated with endometriosis (endometriomas).
• Magnetic resonance imaging (MRI). An MRI is an exam that uses a magnetic field and radio waves to create detailed images of the organs and tissues within your body. For some, an MRI helps with surgical planning, giving your surgeon detailed information about the location and size of endometrial implants.

• Laparoscopy. In some cases, your doctor may refer you to a surgeon for a procedure that allows the surgeon to view inside your abdomen (laparoscopy). While you're under general anesthesia, your surgeon makes a tiny incision near your navel and inserts a slender viewing instrument (laparoscope), looking for signs of endometrial tissue outside the uterus.

  A laparoscopy can provide information about the location, extent and size of the endometrial implants. Your surgeon may take a tissue sample (biopsy) for further testing. Often, with proper surgical planning, your surgeon can fully treat endometriosis during the laparoscopy so that you need only one surgery.

Treatment for endometriosis usually involves medication or surgery. The approach you and your doctor choose will depend on how severe your signs and symptoms are and whether you hope to become pregnant.

Doctors typically recommend trying conservative treatment approaches first, opting for surgery if initial treatment fails.

Pain medication

Your doctor may recommend that you take an over-the-counter pain reliever, such as the nonsteroidal anti-inflammatory drugs (NSAIDs) ibuprofen (Advil, Motrin IB, others) or naproxen sodium (Aleve) to help ease painful menstrual cramps.

Your doctor may recommend hormone therapy in combination with pain relievers if you're not trying to get pregnant.

Hormone therapy

Supplemental hormones are sometimes effective in reducing or eliminating the pain of endometriosis. The rise and fall of hormones during the menstrual cycle causes endometrial implants to thicken, break down and bleed. Hormone medication may slow endometrial tissue growth and prevent new implants of endometrial tissue.

Hormone therapy isn't a permanent fix for endometriosis. You could experience a return of your symptoms after stopping treatment.

Therapies used to treat endometriosis include:

• Hormonal contraceptives. Birth control pills, patches and vaginal rings help control the hormones responsible for the buildup of endometrial tissue each month. Many have lighter and shorter menstrual flow when they're using a hormonal contraceptive. Using hormonal contraceptives — especially continuous-cycle regimens — may reduce or eliminate pain in some cases.
• Gonadotropin-releasing hormone (Gn-RH) agonists and antagonists. These drugs block the production of ovarian-stimulating hormones, lowering estrogen levels and preventing menstruation. This causes endometrial tissue to shrink. Because these drugs create an artificial menopause, taking a low dose of estrogen or progestin along with Gn-RH agonists and antagonists may decrease menopausal side effects, such as hot flashes, vaginal dryness and bone loss. Menstrual periods and the ability to get pregnant return when you stop taking the medication.
• Progestin therapy. A variety of progestin therapies, including an intrauterine device with levonorgestrel (Mirena, Skyla), contraceptive implant (Nexplanon), contraceptive injection (Depo-Provera) or progestin pill (Camila), can halt menstrual periods and the growth of endometrial implants, which may relieve endometriosis signs and symptoms.
• Aromatase inhibitors. Aromatase inhibitors are a class of medicines that reduce the amount of estrogen in your body. Your doctor may recommend an aromatase inhibitor along with a progestin or combination hormonal contraceptive to treat endometriosis.

Conservative surgery

If you have endometriosis and are trying to become pregnant, surgery to remove the endometriosis implants while preserving your uterus and ovaries (conservative surgery) may increase your chances of success. If you have severe pain from endometriosis, you may also benefit from surgery — however, endometriosis and pain may return.

Your doctor may do this procedure laparoscopically or, less commonly, through traditional abdominal surgery in more-extensive cases. Even in severe cases of endometriosis, most can be treated with laparoscopic surgery.

In laparoscopic surgery, your surgeon inserts a slender viewing instrument (laparoscope) through a small incision near your navel and inserts instruments to remove endometrial tissue through another small incision. After surgery, your doctor may recommend taking hormone medication to help improve pain.

Fertility treatment

Endometriosis can lead to trouble conceiving. If you're having difficulty getting pregnant, your doctor may recommend fertility treatment supervised by a fertility specialist. Fertility treatment ranges from stimulating your ovaries to make more eggs to in vitro fertilization. Which treatment is right for you depends on your personal situation.

Hysterectomy with removal of the ovaries

Surgery to remove the uterus (hysterectomy) and ovaries (oophorectomy) was once considered the most effective treatment for endometriosis. But endometriosis experts are moving away from this approach, instead focusing on the careful and thorough removal of all endometriosis tissue.

Having your ovaries removed results in menopause. The lack of hormones produced by the ovaries may improve endometriosis pain for some, but for others, endometriosis that remains after surgery continues to cause symptoms. Early menopause also carries a risk of heart and blood vessel (cardiovascular) diseases, certain metabolic conditions and early death.

Removal of the uterus (hysterectomy) can sometimes be used to treat signs and symptoms associated with endometriosis, such as heavy menstrual bleeding and painful menses due to uterine cramping, in those who don't want to become pregnant. Even when the ovaries are left in place, a hysterectomy may still have a long-term effect on your health, especially if you have the surgery before age 35.

Finding a doctor with whom you feel comfortable is crucial in managing and treating endometriosis. You may want to get a second opinion before starting any treatment to be sure you know all of your options and the possible outcomes.

If your pain persists or if finding a treatment that works takes some time, you can try measures at home to relieve your discomfort.

• Warm baths and a heating pad can help relax pelvic muscles, reducing cramping and pain.
• Over-the-counter nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen (Advil, Motrin IB, others) or naproxen sodium (Aleve), can help ease painful menstrual cramps.

Some report relief from endometriosis pain after acupuncture treatment. However, little research is available on this — or any other — alternative treatment for endometriosis. If you're interested in pursuing this therapy in the hope that it could help you, ask your doctor to recommend a reputable acupuncturist. Check with your insurance company to see if the expense will be covered.

If you're dealing with endometriosis or its complications, consider joining a support group for women with endometriosis or fertility problems. Sometimes it helps simply to talk to other women who can relate to your feelings and experiences. If you can't find a support group in your community, look for one online.

Your first appointment will likely be with either your primary care physician or a gynecologist. If you're seeking treatment for infertility, you may be referred to a doctor who specializes in reproductive hormones and optimizing fertility (reproductive endocrinologist).

Because appointments can be brief and it can be difficult to remember everything you want to discuss, it's a good idea to prepare in advance of your appointment.

What you can do

• Make a list of any symptoms you're experiencing. Include all of your symptoms, even if you don't think they're related.
• Make a list of any medications, herbs or vitamin supplements you take. Include how often you take them and the doses.
• Have a family member or close friend accompany you, if possible. You may get a lot of information at your visit, and it can be difficult to remember everything.
• Take a notepad or electronic device with you. Use it to make notes of important information during your visit.
• Prepare a list of questions to ask your doctor. List your most important questions first, to be sure you address those points.

For endometriosis, some basic questions to ask your doctor include:

• How is endometriosis diagnosed?
• What medications are available to treat endometriosis? Is there a medication that can improve my symptoms?
• What side effects can I expect from medication use?
• Under what circumstances do you recommend surgery?
• Will I take a medication before or after surgery?
• Will endometriosis affect my ability to become pregnant?
• Can treatment of endometriosis improve my fertility?
• Can you recommend any alternative treatments I might try?

Make sure that you understand everything your doctor tells you. Don't hesitate to ask your doctor to repeat information or to ask follow-up questions for clarification.

What to expect from your doctor

Some potential questions your doctor might ask include:

• How often do you experience these symptoms?
• How long have you had these symptoms?
• How severe are your symptoms?
• Do your symptoms seem to be related to your menstrual cycle?
• Does anything improve your symptoms?
• Does anything make your symptoms worse?