The female reproductive system is a very complicated and delicate unit. One of the things to look out for is ovarian cysts. They are sacs with fluid on the surface of an ovary. Many will have these cysts at some point during their child-bearing years. These may not be harmful but in some cases can prove to be a sign of polycystic ovarian syndrome, or PCOS. Ovarian cyst PCOS is a hormonal imbalance that can not only impact menstrual cycles and fertility, but can also lead to major health problems.