This means that the ovary is trying to ovulate and doesn't release the egg or "luteinize", which means become a corpus luteum
. It will then persist or sometimes enlarge. Follicular cysts appear black on ultrasound as they contain only fluid (which transmits the sound better than tissue).
Another type of ovarian cyst
is a hemorrhagic corpus luteum. This too is related to ovulation
. During the release of the egg, the wall of the follicle
may break through a blood vessel causing bleeding in the abdomen or into the cyst cavity
. These will appear acutely often accompanied by pain. On ultrasound they have "mixed echogenicity" meaning a combination of solid and cystic components. Women can have significant bleeding with hemorrhagic cysts particularly if they are on blood thinners
or have bleeding disorders
. Hemorrhagic ovarian cysts will often resolve over time spontaneously and require surgery on some occasions.
Ovarian cyst that continue to enlarge are suspicious for neoplasms
or tumors. These can be benign or malignant (cancerous). A common benign tumor
is a teratoma
, often called a "dermoid" tumor.
For functional cysts (follicular and corpus luteum) prevention is commonly afforded through the use of oral contraceptives.