The endometriomas is the tissue that lines the inside tissue of the uterine cavity. Endometriosis is a disease state in which some of this tissue has spread elsewhere, such as the ovaries, or elsewhere in the abdominal cavity. Endometriosis causes pain in some women and can also cause infertility. However, even the tiniest implant can cause incapacitating pain if it irritates a nearby nerve. Some women with allot of disease may experience no pain.
Larger implants can become locally invasive as they respond to hormone stimulation.
The tissue surrounding the implant can begin to break down and bleed. But if active endometriosis becomes trapped beneath adhesions, enormous pain and pressure can result. Then degeneration and destruction of the localized blood can create a cystic mass called an endometriomas. They can also grow very large, up to the size of a softball. Invasion of nearby structures including the bowel, bladder and urethras can occur.