Endometriosis occurs when tissue like that which lines the inside of uterus grows outside the uterus, usually on the surfaces of organs in the pelvic and abdominal areas, in places that it is not supposed to grow.
The word endometriosis comes from the word “endometrium”—endo means “inside” and metrium (pronounced mee-tree-um) means “mother.” Health care providers call the tissue that lines the inside of the uterus (where a mother carries her baby) the endometrium.
Health care providers may call areas of endometriosis by different names, such as implants, lesions, or nodules.
In what places, outside of the uterus, do areas of endometriosis grow?
Most endometriosis is found in the pelvic cavity:
- On or under the ovaries
- Behind the uterus
- On the tissues that hold the uterus in place
- On the bowels or bladder
In extremely rare cases, endometriosis areas can grow in the lungs or other parts of the body.
What are the symptoms of endometriosis?
One of the most common symptoms of endometriosis is pain, mostly in the abdomen, lower back, and pelvic areas. The amount of pain a woman feels is not linked to how much endometriosis she has. Some women have no pain even though their endometriosis is extensive, meaning that the affected areas are large, or that there is scarring. Some women, on the other hand, have severe pain even though they have only a few small areas of endometriosis.
General symptoms of endometriosis can include (but are not limited to):
- Extremely painful (or disabling) menstrual cramps; pain may get worse over time
- Chronic pelvic pain (includes lower back pain and pelvic pain)
- Pain during or after sex
- Intestinal pain
- Painful bowel movements or painful urination during menstrual periods
- Heavy menstrual periods
- Premenstrual spotting or bleeding between periods
In addition, women who are diagnosed with endometriosis may have gastrointestinal symptoms that resemble a bowel disorder, as well as fatigue.
Who gets endometriosis?
Endometriosis can affect any menstruating woman, from the time of her first period to menopause, regardless of whether or not she has children, her race or ethnicity, or her socio-economic status. Endometriosis can sometimes persist after menopause; or hormones taken for menopausal symptoms may cause the symptoms of endometriosis to continue.
Current estimates place the number of women with endometriosis between 2 percent and 10 percent of women of reproductive age. But, it’s important to note that these are only estimates, and that such statistics can vary widely.
Does having endometriosis mean I’ll be infertile or unable to have children?
About 30 percent to 40 percent of women with endometriosis are infertile, making it one of the top three causes of female infertility. Some women don’t find out that they have endometriosis until they have trouble getting pregnant.
If you have endometriosis and want to get pregnant, your health care provider may suggest that you have unprotected sex for six months to a year before you have any treatment for the endometriosis.
The relationship between endometriosis and infertility is an active area of research. Some studies suggest that the condition may change the uterus so it does not accept an embryo. Other work explores whether endometriosis changes the egg, or whether endometriosis gets in the way of moving a fertilized egg to the uterus.
What causes endometriosis?
We don’t know the exact cause of endometriosis. Right now, a number of theories try to explain the disease.
Endometriosis may result from something called “retrograde menstrual flow,” in which some of the tissue that a woman sheds during her period flows into her pelvis. While most women who get their periods have some retrograde menstrual flow, not all of these women have endometriosis. Researchers are trying to uncover what other factors might cause the tissue to grow in some women, but not in others.
Another theory about the cause of endometriosis involves genes. This disease could be inherited, or it could result from genetic errors, making some women more likely than others to develop the condition. If researchers can find a specific gene or genes related to endometriosis in some women, genetic testing might allow health care providers to detect endometriosis much earlier, or even prevent it from happening at all.
Researchers are exploring other possible causes, as well. Estrogen, a hormone involved in the female reproductive cycle, appears to promote the growth of endometriosis. Therefore, some research is looking into endometriosis as a disease of the endocrine system, the body’s system of glands, hormones, and other secretions. Or, it may be that a woman’s immune system does not remove the menstrual fluid in the pelvic cavity properly, or the chemicals made by areas of endometriosis may irritate or promote growth of more areas. So, other researchers are studying the role of the immune system in either stimulating, or reacting to endometriosis.
Other research focuses on determining whether environmental agents, such as exposure to man-made chemicals, cause endometriosis. Additional research is trying to understand what, if any, factors influence the course of the disease. We just don’t have answers on the causes yet.
Another important area of NICHD research is the search for endometriosis markers. These markers are substances made by or in response to endometriosis that health care providers can measure in the blood or urine. If markers are found, health care providers could diagnose endometriosis by testing a woman’s blood or urine, which might reduce the need for surgery.
How do I know that I have endometriosis?
Currently, health care providers use a number of tests for endometriosis. Sometimes, they will use imaging tests to produce a “picture” of the inside of the body, which allows them to locate larger endometriosis areas, such as nodules or cysts. The two most common imaging tests are ultrasound, a machine that uses sound waves to make the picture, and magnetic resonance imaging (MRI), a machine that uses magnets and radio waves to make the picture.
The only way to know for sure that you have the condition is by having surgery. The most common type of surgery is called laparoscopy. In this procedure, the surgeon inflates the abdomen slightly with a harmless gas. After making a small cut in the abdomen, the surgeon uses a small viewing