Most go in months and this size is very rare

AN ovarian cyst is a fluid-filled sac that develops on an ovary.

The majority are non-cancerous and disappear within a few months without needing any treatment. If cysts are large, causing symptoms, or potentially cancerous, surgery may be needed to remove them.

A cyst of this size is very rare. If not removed, a woman would likely suffer symptoms including pain and possible problems with bladder and bowel function. The cyst may have twisted at any stage, causing pain and possibly resulting in death of the ovary and its surrounding tissues.

This may have led to surgery to remove the dead ovary and surrounding tissue.