In this condition factsheet:
The Facts on Endometriosis
The endometrium is the tissue that lines the inside of the uterus (the womb). It is the tissue that is shed each month when women menstruate. Each month it builds up rapidly in preparation for pregnancy, and each month the excess endometrial tissue is sloughed off during menstruation if pregnancy does not occur.
In endometriosis, endometrial cells are found outside the uterus, usually in other parts of the abdomen. These cells respond to female hormones in the same way as the lining of the uterus does. Each month, tissue builds up, breaks down, and sheds. Unlike the cells inside the uterus, the blood and tissue that are shed in the abdomen have no way of leaving the body. They stick to other tissue and sometimes start to divide and multiply. They may grow into other tissue, or form strands that bind organs together. They may create scar tissue, which can be painful. Sometimes the endometrial cells create cysts that can rupture and bleed.
The process sounds a bit like cancer, but endometriosis isn't cancer. However, it may very slightly increase the risk of getting certain cancers. Endometriosis isn't a fatal disease but can be widespread. About 10% to 15% of actively menstruating women between the ages of 25 and 44 have endometriosis. About one-quarter to one-half of infertile women have the disease.
Causes of Endometriosis
Various theories have tried to explain endometriosis. Most involve the idea of retrograde flow. During menstruation, the endometrium sheds its top layers. These layers normally leave the body. The tissue and blood is forced out by muscle contractions. Sometimes, however, it flows backwards, going up the fallopian tubes towards the ovaries. In this way, endometrial cells could reach both the ovaries and the pelvic cavity, areas that are outside of the uterus.
Retrograde flow doesn't explain everything though, because it's often seen in women without endometriosis. Another theory involves the immune system. Immune system disorders mean the body may not able to find and destroy endometrial tissue that's outside the uterus. There are measurable differences in the immune systems of women with endometriosis, but we don't know yet what the significance is.
Endometriosis may have a genetic component. The daughters and sisters of women with endometriosis are at a slightly higher risk of getting the disease.
Another theory of endometriosis suggests that it spreads through the blood or lymphatic vessels. There is also the possibility that normal tissue inside the abdominal cavity may change and become endometriosis.
Symptoms and Complications of Endometriosis
Symptoms of endometriosis include:
- pelvic pain
- pain during sex
- changes in menstruation
- pain and cramps during menstruation
- painful urination or bowel movements during periods
Many of these symptoms can also be associated with other health conditions. The severity of symptoms is not necessarily related to the amount of endometrial tissue found outside the uterus. Some women with endometriosis throughout the pelvis feel nothing at all, while others with less tissue found outside the uterus experience a great deal of pain.
Menstrual cramping that worsens after years of less painful periods may be a sign of endometriosis.
Cysts and scar tissue can form around the vagina in the abdomen, which can make sexual intercourse painful. Pain during sex is a possible indicator of endometriosis, but it's a symptom of other conditions, too. Endometrial tissue often ends up in one or both ovaries of women with endometriosis. There it can form cysts called endometriomas.