The cause of endometriosis is not known. But there are some theories and research is ongoing. Endometriosis is likely caused by a mix of different things.
Genetics
You are more likely to have endometriosis if someone in your family has it.
Retrograde menstruation
Retrograde menstruation is when some of the uterus lining (endometrial tissue) flows back through the fallopian tubes. Normally, this tissue should leave your body during a period. Instead, the tissue sticks to organs in the pelvis. Over time, this tissue can become inflamed and cause pain.
Other causes
Other possible causes of endometriosis include:
- metaplasia - normal tissues outside the uterus turn into endometrial tissue
- immune system - there is a problem with the body's natural defence against illness and infection
- tissue cells travel around the body in the bloodstream or lymphatic system (a series of tubes and glands that form part of the immune system)
Content supplied by the NHS and adapted for Ireland by the HSE
