If you have endometriosis, you know it causes pain and cramping, which can sometimes be severe, especially during your period. It can even create problems when you want to have a baby. But what exactly is endometriosis and what causes all the symptoms that are associated with it?

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Endometriosis occurs when tissue that should line the inside of your uterus, the endometrium, grows outside of it instead. Even though the tissue is outside of your uterus, it still acts like it should during your menstrual cycles. That means at the end of your period, this tissue will break apart and bleed.

However, the blood from this tissue has no place to go. Surrounding areas may become inflamed or swollen, and scar tissue and lesions can develop. The most common site for endometriosis is on your ovaries.