Imagine the tissue that normally lines the inside of your uterus (the endometrium) begins to grow in places where it shouldn’t, such as on your ovaries, fallopian tubes, or the lining of your pelvis. This is endometriosis. Each month, this misplaced tissue behaves just like the lining of your uterus; it thickens, breaks down, and bleeds during your menstrual cycle. However, because this blood has no way to exit the body, it gets trapped. This leads to inflammation, severe pain, and the formation of scar tissue (adhesions), which can interfere with fertility.