What causes corpus luteum cysts?

What causes corpus luteum cysts?

A corpus luteum cyst forms in your ovaries when your corpus luteum keeps growing instead of breaking down, such as in pregnancy. Each menstrual cycle, a sac in one of your ovaries called a follicle creates and releases an egg. Soon after, your corpus luteum forms at the break of the follicle where the egg escaped. If the egg gets fertilized, your corpus luteum creates a hormone called progesterone that changes your uterus. Progesterone makes the lining of your uterus thicker so that a fertilized egg can take hold there. It creates a healthy environment inside your uterus where the egg becomes a fetus.

Your corpus luteum goes away when you don’t need the progesterone it’s making to support pregnancy. If you’re pregnant, your corpus luteum usually goes away around week 12, when the placenta starts making enough progesterone to keep the fetus healthy. If the egg doesn’t get fertilized, your corpus luteum usually goes away 10 days after the egg left your ovary.

You get a corpus luteum cyst when the corpus luteum fills with fluid and expands, but generally, it will self-resolve (reabsorb).