What Is Endometriosis?
Endometriosis is a common gynecological condition. It's a chronic, painful and often progressive disease in women.
Normally, the tissue that lines a woman's uterus, known as the endometrium, is found only in the uterus and is expelled from the body with each menstrual cycle. However, when a woman develops endometriosis, microscopic bits of this tissue escape from the uterus backwards into the abdomen and stick and grow on other abdominal/pelvic organs.
These endometrial cells usually implant throughout the pelvis, often involving other portions of the reproductive system, such as the ovaries, the outer wall of the uterus, the ligaments that support the uterus and the space between the uterus and the rectum. In rare cases, they can spread outside the abdomen and affect other organs, such as the lungs.
Like the endometrium itself, the transplanted tissue responds to the hormones estrogen and progesterone by thickening and may bleed every month. But because the transplanted tissue is embedded in other tissues, the blood it produces cannot escape. This causes irritation of the surrounding tissue which in turn causes cysts, scars and the fusing of body tissues. This can eventually bind the reproductive organs together so that they move as one mass when manipulated by a doctor. This can severely distort the normal anatomy of the pelvis and consequently have an extremely negative impact on fertility. Cases of endometriosis are classified as minimal, mild, moderate or severe, depending on the size of the lesions and how deeply they reach into the other organs. They are also referred to as stage I-IV. This is considered a benign condition.
It's estimated that endometriosis affects 3-10% of women of reproductive age, and 25-35% of infertile women. In women suffering from pelvic pain the prevalence is about 40-60%. The average age at diagnosis is between 20 and 29, with similar rates within races in socioeconomic status. Symptoms usually diminish at menopause, with the marked decline in the production of estrogen.
Normally, the tissue that lines a woman's uterus, known as the endometrium, is found only in the uterus and is expelled from the body with each menstrual cycle. However, when a woman develops endometriosis, microscopic bits of this tissue escape from the uterus backwards into the abdomen and stick and grow on other abdominal/pelvic organs.
These endometrial cells usually implant throughout the pelvis, often involving other portions of the reproductive system, such as the ovaries, the outer wall of the uterus, the ligaments that support the uterus and the space between the uterus and the rectum. In rare cases, they can spread outside the abdomen and affect other organs, such as the lungs.
Like the endometrium itself, the transplanted tissue responds to the hormones estrogen and progesterone by thickening and may bleed every month. But because the transplanted tissue is embedded in other tissues, the blood it produces cannot escape. This causes irritation of the surrounding tissue which in turn causes cysts, scars and the fusing of body tissues. This can eventually bind the reproductive organs together so that they move as one mass when manipulated by a doctor. This can severely distort the normal anatomy of the pelvis and consequently have an extremely negative impact on fertility. Cases of endometriosis are classified as minimal, mild, moderate or severe, depending on the size of the lesions and how deeply they reach into the other organs. They are also referred to as stage I-IV. This is considered a benign condition.
It's estimated that endometriosis affects 3-10% of women of reproductive age, and 25-35% of infertile women. In women suffering from pelvic pain the prevalence is about 40-60%. The average age at diagnosis is between 20 and 29, with similar rates within races in socioeconomic status. Symptoms usually diminish at menopause, with the marked decline in the production of estrogen.
What Causes Endometriosis?
Researchers do not know exactly why or how endometrial tissue reaches other parts of the body. One likely possibility involves a condition known as retrograde, or backward, menstruation. Normally during menstruation, portions of the sloughed-off uterine lining exit the uterus through the cervix and the vagina. But in retrograde menstruation, fragments of the endometrium flow back through the fallopian tubes and may then be carried into the abdominal cavity, giving rise to endometriosis. Doctors have found that endometriosis occurs more often in women with physical conditions that increase retrograde menstruation, such as obstructions in the vagina and cervix.
In the rare cases of endometriosis affecting the lungs or other tissue far from the uterus, researchers speculate that the stray endometrial fragments travel through the bloodstream or the lymphatic system, although no one knows just how this happens.Another theory suggests that endometrial tissue migrates outside the uterus on a fairly routine basis but develops into endometriosis only in women who have an immune system problem that prevents the body from destroying the displaced fragments.
Despite uncertainty about the specifics on why endometriosis develops, researchers have noticed some trends. The condition tends to run in families, which suggests that genetic influences play a role. Studies have also shown that endometriosis occurs more often in women who have a shorter-than-normal menstrual cycle or a longer-than-normal flow: Women who have fewer than 25 days between periods or who menstruate for more than seven days are twice as likely to develop endometriosis. Recent evidence also points to exposure to dioxin, an industrial chemical, as a possible cause.
There seems to be no direct relationship between the size of lesions and the severity of pelvic pain. Some women with small lesions report debilitating pain, while others with extensive lesions have no symptoms. Pain probably comes from the scarring and irritation caused by bleeding, or from endometrial tissue invading or growing on a nerve.
How the disease causes infertility also is unclear. In severe cases of endometriosis, stage IV anatomic distortion and adhesions have been implicated. Also destruction of the ovary by the endometriosis forming endometriomas places these women at increased risk for surgery and possible removal of ovaries. Data from women undergoing invitro fertilization treatment supports the notion that women with stage III and IV endometriosis have poor ovarian reserve. This does not explain why many women with tiny lesions are infertile.
Some investigators think the endometrial implants upset the process of ovulation. The implants may also hinder passage of the egg through the fallopian tubes by interfering with the tiny waving hairs responsible for moving the egg. Other research suggests that endometrial implants secrete chemicals that create an environment hostile to fertilization. But more study is needed to provide answers.
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