Endometriosis is commonly found in the pelvis and is a condition where cells similar to those found lining the womb (uterus) are found in other parts of the body. Besides the pelvis, which includes inside or on the ovaries, behind the uterus and on the bowel and bladder, endometriosis can also be found in the lungs, chest cavity, abdominal wall scars, the navel and elsewhere in the body.
Each month that a woman is not pregnant, the uterus lining breaks down and becomes a menstrual period. The endometriosis tissue goes through a similar cycle and bleeds during menstruation. This usually causes pain during periods, inflammation and scarring and can cause organs or structures to stick to each other and can lead to distortion of the normal anatomy. This cyclical pattern is believed to be a major contributing factor in the development of symptoms associated with endometriosis.
It is not known what causes endometriosis, however there are some factors that may contribute to it and these may be inherent in families. Two popular theories are:
- Retrograde Menstruation. This is a popular theory that states that endometriosis occurs when cells that line the womb go backwards through the fallopian tubes into the pelvis during a normal menstrual period.
- Metaplasia. This describes a process which involves cells that are situated in the pelvis and abdomen which change, for reasons that are not fully understood, into endometrial type cells.