Introduction
Endometriosis is small deposits of the womb lining (endometrium) that are located outside of the normal womb cavity. The most common place to find it is on the ovary, the back of the uterus and the tissues that support the uterus in its normal position (uterosacral ligaments). It can also be found on the thin lining of the pelvic organs (the peritoneum), on the tubes, between the vagina and rectum (rectovaginal septum), in or on the bladder, in abdominal scars from previous surgery and even as far away from the pelvis as the lung!
Each time that you have a normal period, so this endometriosis does also, and this leads to cyclical swelling, stretching of tissues, inflammation and scarring. Eventually all the scarring and inflammation can lead to symptoms even when you're not having a period.
It is more common in women whose relatives have endometriosis, if you have cycles shorter than 28 days and women who bleed on a period for longer than a week. Many cases occur in women without these associations, of course, and not all women who fit into the above categories necessarily get endometriosis.
What causes endometriosis?
There are several theories behind this, one possible cause is called retrograde menstruation. Normally during a period the menstrual blood comes out of the cervix and into the vagina. In around 75% of women, a small amount of blood flows backwards down the fallopian tubes and into the pelvic cavity. This blood contains tiny seedlings of the lining of the womb or endometrium. It is not known why in some women this might implant and lead to endometriosis, but not in others - it may have something to do with a particular woman's immune response and ability to fight off & remove these seedlings.
Another theory suggests that because the uterus, tubes, peritoneum and part of the ovary are all developed from the same area in the fetus, endometriosis might be caused by some cells taking the wrong turn during development.
Yet another idea rests on the fact that endometrial tissue from the lining of the womb can be found in the blood stream. It might be that these small deposits end up in other areas far from the womb and grow from there. This would explain the rare finding of endometriosis in places such as the lung.
Most likely there is no one simple answer to explain it, and the true cause is a combination of all these.
What problems can it cause?
The most common problems are:
- Pelvic pain
- Painful periods
- Pain during intercourse
- Infertility
The pelvic pain caused by endometriosis can be very variable. It may be like a dull ache located generally over the lower abdomen, or may be more severe. It can be more localised into the rectum (back passage) or cause urinary symptoms. Sometimes the degree of pain felt by a woman is not related to the extent of disease found when the endometriosis is diagnosed. Some women have very bad endometriosis, but their pain & discomfort is minimal. Others have only a few spots noted and the pain is severe. In general, however, the more endometriosis that is present, the more likely you are to have symptoms. It is probably more to do with how deep the endometriosis is buried.
Painful periods are often the first sign a woman might have that endometriosis is present. The pain usually begins a few days before the period is due and continues throughout the period. It is typically located in the centre of the pelvis, but can be one-sided. It may go into the back or down the legs.
Pain on intercourse is often worse with a particular position and especially with deep penetration. Many women experience an aching in the pelvis after intercourse.
The link between endometriosis and infertility is sometimes difficult to explain. When the disease is so bad that there is scarring around the tubes, or there are ovarian cysts, it is not surprising that this might interfere with normal fertility. It is less clear how only a few small spots of endometriosis might have an effect on falling pregnant. Nevertheless, studies have found that endometriosis is more common in women who have difficulty conceiving, supporting the link. Also, another major study looking at treatment of mild to moderate endometriosis did find an improved chance of falling pregnant in women who received treatment.
Other symptoms
Although the above problems are most common, some women experience other symptoms related to where endometriosis might have implanted:
- painful bowel movements (known as dyschezia) or passing blood in the stools
- bloating
- constipation
- painful pelvic exams
- painful and frequent urination, or bleeding when passing water during the time of the period
Next: Diagnosis and staging
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