A corpus luteum cyst is a type of ovarian cyst that forms after ovulation, when the follicle that released the egg becomes filled with fluid. It usually does not cause any symptoms and goes away on its own within a few months. However, in rare cases, it can rupture, bleed, or twist, causing severe pain and other complications. A corpus luteum cyst is important for pregnancy, as it produces the hormone progesterone that supports the development of the fetus. A corpus luteum cyst is one of the most common types of cysts found in the ovaries during the first trimester of pregnancy. If you have a corpus luteum cyst, you should get regular pelvic exams and monitor for any changes in your condition. If you experience sudden, severe abdominal or pelvic pain, fever, vomiting, or signs of shock, you should seek immediate medical help.