Endometriosis is a common and often painful condition that affects around 10% of women in their menstruating years. It can happen any time from when periods start right up to the time of menopause.
Endometriosis happens when the tissue lining the uterus (the endometrium) is found outside the uterus, where it implants and starts to grow and function.
Symptoms can include:
For more information on endometriosis, see the Jean Hailes Foundation's endometriosis website.