A corpus luteum cyst is considered to be a functional, or simple, ovarian cyst. A corpus luteum cyst may develop after an egg has been released from the follicle. Ideally after the release of an egg, the follicle will become what is called the corpus luteum. If fertilization occurs and a pregnancy results, the corpus luteum will work in providing the young embryo with progesterone until the placenta can take over later in the first trimester. However, if pregnancy does not result the corpus luteum should shrink and dissolve. In some cases the corpus luteum will continue to grow and may fill with fluid or blood. It will then be considered to be a corpus luteum cyst. A corpus luteum cyst, although usually rather small, can continue to grow, sometimes causing much pain and discomfort. If the cyst does not dissolve on its own, which is often the case, a simple laparoscopic surgery, to remove the cyst, may be suggested.