A condition in which fragments of the endometrium (the lining of the inside of the uterus) are found in other parts of the body, usually in the pelvic cavity. Endometriosis can cause infertility in up to two in five affected women.

Incidence and causes 

Endometriosis most commonly occurs in women who are aged between 25 and 40. The cause of the disorder is not clear. In some cases, it is thought to be due to the failure of certain fragments of the endometrium, shed during menstruation, to leave the body. Instead, they travel up the fallopian tubes and into the pelvic cavity, where they can adhere to and grow on any pelvic organ. These displaced patches of endometrium continue to respond to hormones that are produced in the menstrual cycle and bleed each month. 


The symptoms of endometriosis vary greatly. Some women have no symptoms, but the disorder most commonly causes abnormal or heavy menstrual bleeding. There may be severe abdominal pain and/or lower back pain during menstruation. Other possible symptoms include dyspareunia (painful sexual intercourse), diarrhoea, constipation, and pain during defaecation. The internal bleeding causes pain and is followed by healing, which produces internal scarring. Bleeding into an ovary may result in a blood-filled ovarian cyst (known as a “chocolate cyst” because of its appearance). Endometrial tissue may be deposited in the muscular wall of the uterus (myometrium); this condition is called adenomyosis. In rare cases, there is bleeding from the rectum during menstruation. 

Diagnosis and treatment

Laparoscopy (examination of the abdominal cavity with a viewing instrument) confirms the diagnosis. Certain drugs (including danazol, progestogen drugs, gonadorelin analogues, or the combined oral contraceptive pill) may be given to prevent menstruation. Local ablation of the endometrial deposits, using either laser treatment or electrocautery (the application of heat produced by an electric current), may sometimes be needed. If the woman is fertile, pregnancy often results in significant improvement. A hysterectomy (surgical removal of the uterus) and oophorectomy (surgical removal of the ovaries) may be offered if the woman does not have plans to have children.

Read more:

Endometriosis in more detail


Endometriosis is a condition in which bits of the tissue similar to the tissue lining the uterus (endometrium) grow in other parts of the body


It is difficult to determine the exact number of women who have endometriosis because some never show symptoms, but estimates suggest that 6–8% of women of childbearing age in the United States have the condition. It most commonly is diagnosed in women between the ages of 25 and 40. Endometriosis can appear in the teenage girls, but rarely before the start of menstruation. It is seldom seen in postmenopausal women and occurs independent of race or ethnicity. The prevalence of endometriosis in the United States has remained stable since the early 1980s.


Endometrial tissue like that lining the uterus sometimes develops in other parts of the body. These patches of misplaced endometrial tissue are called implants. Like the endometrial lining the uterus, this tissue builds up and sheds in response to monthly hormonal cycles (menstruation). However, there is no natural outlet for the material from these implants. Instead, it moves onto surrounding tissues, causing swelling, inflammation, and often pain. Repeated irritation leads to the development of scar tissue and adhesions in the area of the endometrial implants. Depending on their location, these scars may interfere with a woman’s ability to conceive a child.

Endometrial implants are found most often on the pelvic organs—the ovaries, Fallopian tubes, and in the cavity behind the uterus. They can also be found on organs in the abdominal cavity such as the bladder and large intestine (colon). Occasionally, this tissue grows in distant parts of the body such as the lungs, arms, and kidneys.

Endometriosis is a progressive condition that usually advances slowly, over the course of many years. Doctors rank cases from minimal to severe based on factors such as the number and size of the endometrial implants, their appearance and location, and the extent of the scar tissue and adhesions in the vicinity of the growths.

Risk factors

If a first-degree female relative (mother, sister) has endometriosis, a woman has a higher risk of also developing the disorder. Another possible risk factor is the length of a woman’s menstrual cycle. Women whose periods last longer than a week with an interval of less than 27 days between them seem to be more prone to the condition. This corresponds with studies that show that women with the most stable hormone levels are less likely to develop endometriosis. In addition, some studies have found that women who are tall and thin with a lower than average body mass index (BMI) are more likely to develop endometriosis, although there is no understanding of why this occurs.

Causes and symptoms

Endometriosis was once called the ‘‘career woman’s disease’’ because it was thought to be a product of delayed childbearing. The statistics defy such a narrow generalization; however, the hormonal changes that accompany pregnancy may slow the progress of the condition.

Although the exact cause of endometriosis is unknown, several theories have been put forward to explain the origins of the disorder. These include:

  • Retrograde (reverse) menstruation theory. Originally proposed in the 1920s, this theory states that a partial reversal in the direction of menstrual flow (a common event) sends discarded endometrial cells into the Fallopian tubes and then into the body cavity where they attach to internal organs and seed endometrial implants. There is considerable evidence to support this explanation. Reversed menstrual flow occurs in 70–90% of women and is thought to be more common in women with endometriosis. However, this does not explain why many women with retrograde menstrual flow do not develop endometriosis.
  • Vascular-lymphatic theory. This theory suggests that the lymph system or blood vessels (vascular system) is the vehicle for the distribution of endometrial cells out of the uterus.
  • Coelomic metaplasia theory. The endometrium and the peritoneal mesothelium arise from the same embryonic cells called coelomic wall epithelium. According to this hypothesis, some cells in the peritoneal mesothelium retain their embryonic ability to transform into endometrium, either spontaneously or after chronic irritation caused by exposure to retrograde menstrual flow.
  • Iatrogenic theory. Iatrogenic disorders are those caused by the action of a physician. This theory suggests that surgery or procedures in the region of the woman’s reproductive organs either deposits endometrial cells in inappropriate places where they grow or in some stimulates other cells to develop into endometrium.

In addition to these theories, the following factors are thought to influence the development of endometriosis:

  • Heredity. A woman’s chance of developing endometriosis is seven times greater if her mother or sisters have the disease.
  • Immune system function. Women with endometriosis may have lower functioning immune systems that have trouble eliminating stray endometrial cells. This would explain why a high percentage of women experience reversed menstrual flow while relatively few develop endometriosis.
  • Dioxin exposure. Some research suggests a link between the exposure to dioxin (TCCD), a toxic chemical found in weed killers, and the development of endometriosis.

While many women with endometriosis suffer debilitating chronic or acute pain symptom, others have none and are unaware they have the disorder. There does not, however, seem to be any relation between the severity of the symptoms and the extent of the disorder.

The most common symptoms of endometriosis are:

  • Menstrual pain (dysmenorrhea). Pain in the lower abdomen that begins a day or two before the menstrual period starts and continues through to the end is typical of endometriosis. Some women also report lower back aches and pain during urination and bowel movement, especially during their periods.
  • Painful sexual intercourse. Pressure on the vagina and cervix causes severe pain for some women.
  • Abnormal bleeding. Heavy menstrual periods, irregular bleeding, and spotting are common features of endometriosis.
  • Infertility. There is a strong association between endometriosis and infertility, although the reasons for this have not been fully explained. It is thought that the build up of scar tissue and adhesions blocks the Fallopian tubes and prevents the ovaries from releasing eggs. Endometriosis may also affect fertility by causing hormonal irregularities and a higher rate of early miscarriage.


If a doctor suspects endometriosis, the first step will be to perform a pelvic exam to try to feel if implants are present. Very often there is no strong evidence of endometriosis from a physical exam.


The only way to make a definitive diagnosis is through minor surgery called a laparoscopy. A laparoscope, a slender scope with a light on the end, is inserted into the woman’s abdomen through a small incision near her belly button. This allows the doctor to examine the internal organs for endometriotic growths. Often, a sample of tissue (biopsy) is taken for later examination in the laboratory. Endometriosis is sometimes unintentionally discovered when a woman has abdominal surgery for another reason such as tubal ligation or hysterectomy.

Various imaging techniques such as transvaginal ultrasonography or endorectal ultrasonography, computed tomography scan (CT scan), magnetic resonance imaging (MRI) can offer some additional information but are not useful in making the initial diagnosis. They may be done, however, to rule out other conditions with similar symptoms. Various other tests such as a pregnancy test, may also be done to rule out other conditions. A test for the blood protein CA125 is not useful in making the initial diagnosis, but testing for this substance before and after treatment can predict a recurrence of the disease.


How endometriosis is treated depends on the woman’s symptoms, her age, the extent of the disease, and her personal preferences. The condition cannot be fully eradicated without surgery. Conservative treatment focuses on managing the pain, preserving fertility, and delaying the progress of the condition.


Over-the-counter pain relievers such as aspirin and acetaminophen (Tylenol) are useful for mild cramping and menstrual pain. )ver-the-counter or prescription-strength nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen (Motrin, Advil) and naproxen (Aleve, Naprosyn), may be effective. If pain is severe, a doctor may prescribe narcotic pain medications, although these can be addicting and are rarely used.

Hormonal therapies may effectively treat symptoms of endometriosis, but they also act as contraceptives. Before beginning hormone treatment, a woman should discuss her reproductive plans with her physician.

The following hormonal treatments may be used to treat endometriosis:

  • Oral contraceptives. Continuously taking estrogenprogestin pills tricks the body into thinking it is pregnant. This state of pseudo pregnancy may result in pelvic pain and a temporary withering of endometrial implants.
  • Danazol (Danocrine) and gestrinone are synthetic male hormones that lower estrogen levels, prevent menstruation, and shrink endometrial tissues. Negative side effects include weight gain and menopauselike symptoms and cause some women to develop masculine characteristics.
  • Progestins. Medroxyprogesterone (Depo-Provera) and related drugs also may be used in treating endometriosis. They have been proven effective in minimizing pain and halting the progress of the condition but are rarely used because of the high rate of side effects.
  • Gonadotropin-releasing hormone (GnHR) agonists. These estrogen-inhibiting drugs successfully limit pain and prevent the growth of endometrial implants. They can cause menopause symptoms, however, and doses have to be closely regulated to prevent bone loss associated with low estrogen levels.


Removing the uterus, ovaries, and Fallopian tubes is the only permanent method of eliminating endometriosis. This is an extreme measure that deprives a woman of her ability to bear children and forces her body into early menopause. In some cases, endometrial implants can be removed with laser surgery performed through a laparoscope. For women with minimal endometriosis, this technique usually is successful in reducing pain and slowing the condition’s progress. It may help infertile women increase their chances of becoming pregnant.

Alternative therapies

Although severe endometriosis should not be self treated, many women find they can help relieve symptoms through alternative therapies. In a survey conducted by the Endometriosis Association, 40% to 60% of the women who used alternative medicines reported relief of pain and other symptoms.


A high-fiber diet, particularly from grains and beans, may decrease cramping and inflammation. The oils in seeds, nuts, and certain fish (cod, salmon, mackerel, and sardines) may help to relieve cramping. Carrots, beets, lemons, cauliflower, Brussels sprouts, cabbage, onions, garlic, citrus fruits, vegetables, chicory, radicchio, and yogurt may help to reduce symptoms Sugar and animal fats can increase inflammation and aggravate pain. Milk and meat may contain hormones, so these should be avoided. Vegetarian or vegan diets may be recommended for those with endometriosis. Occasionally, an allergy elimination diet may be recommended.


The following supplements can be used to treat endometriosis:

  • vitamin B complex to help the liver break down excess estrogen
  • vitamin C to reduce heavy menstrual bleeding
  • calcium
  • bioflavonoids to help reduce heavy menstrual bleeding
  • magnesium to relieve pain and flush out toxins
  • vitamin E to heal inflamed tissues
  • iron for anemia resulting from heavy bleeding
  • lipotropic factors (Choline, methionine, and inositol enhance liver function)
  • fish oil capsules, flax oil, or any essential fatty acid to reduce cramping
Herbal remedies 

Several herbal remedies for endometriosis exist. The first four in this list are the most commonly used remedies:

  • Genistein (soy/isoflavone) helps the body excrete excess estrogen and possibly blocks estrogen’s effect.
  • Cramp bark (Viburnum opulus) helps ease cramping
  • Dong quai (Angelica sinensis)balances hormone levels and reduces inflammation.
  • Black cohosh Cimicifuga racemosa) helps the body excrete excess estrogen and improves the health of pelvic organs.
  • Red clover (Trifolium pratense) balances hormone levels.
  • Milk thistle (Silybum marianum) may improve liver function.
  • Life root (Senecio aureus) may improve the health of pelvic organs
  • Feverfew (Chrysanthemum parthenium) eases pain and cramping.
  • Dandelion eases pain and cramping and supports the liver.
  • Yarrow (Archillea millefolium) eases cramping and restores hormonal balance.
  • Evening primrose (Oenothera biennis) oil relieved endometriosis symptoms in 90% of patients in one study.
  • Shepherd’s purse (Capsella bursa-pastoris) reduces heavy menstrual bleeding and tones the uterus.
  • Meadowsweet (Filipendula ulmaria) reduces pain.
Other therapies 

Other remedies for endometriosis include acupuncture or acupressure to relieve pain, visualization, guided imagery, naturopathy, homeopathy (Lilium tigrum, sepia, and belladonna), hydrotherapy, exercise, and meditation.

Home remedies

Studies have shown that by gradually increasing their level of physical activity some women are able to reduce their level of pelvic pain. However, for unknown reasons, this does not work for all women.


Most women who have endometriosis have minimal symptoms and do well with conservative treatment. Overall, endometriosis symptoms recur in an average of 40% of women over the five years following treatment. With hormonal therapy, pain returned after five years in 37% of patients with minimal symptoms and 74% of those with severe cases. The highest success rate followed complete removal of implants using laser surgery. Eighty percent of these women were still pain-free five years later. In cases that do not respond to these treatments, a woman and her doctor may consider surgery to remove her reproductive organs. The most serious complication from endometriosis is reduced fertility or complete infertility.


There is no proven way to prevent endometriosis.

Key terms

Adhesions—Web-like scar tissue that may develop as a result of surgery or a disease such as endometriosis and bind organs to one another.

Endometrial implants—Growths of endometrial tissue that attach to organs, primarily in the pelvic cavity.

Endometrium—The tissue lining the uterus that grows and sheds each month during a woman’s menstrual cycle.

Estrogen—Any of several steroid hormones, produced mainly in the ovaries, that stimulate the development of the endometrium and the development of female secondary sexual characteristics.

Hormonal therapy—Use of hormone medications to inhibit menstruation and relieve the symptoms of endometriosis.

Iatrogenic—Resulting from the activity of the physician.

Laparoscopy—A diagnostic procedure, which when performed for endometriosis performed by inserting a slender, wand-like instrument through a small incision in the woman’s abdomen.

Menopause—The end of a woman’s menstrual periods when a woman no longer can conceive a child.

Retrograde menstruation—Menstrual flow that travels into the body cavity rather than being expelled through the uterus.