It is a condition in which bits of the tissue that forms the lining of the uterus (endometrium) grows outside of the pelvic cavity; like the uterine linings, this tissue builds up and sheds responding to the monthly hormonal cycles. However, there is no natural channel for the blood discarded from these implants. Instead, it spreads onto surrounding organs, causing inflammation and swelling. Because of this repeated irritation scar tissue and adhesions develops in the area of the endometrial implants.