Each month, a mature ovarian follicle ruptures, releasing an ovum so the process of fertilization can begin. Occasionally, these follicles may bleed into the ovary, causing cortical stretch and pain, or at the rupture site following ovulation. Similarly, a corpus luteum cyst may bleed subsequent to ovulation or in early pregnancy. As blood accumulates in the peritoneal cavity, abdominal pain and signs of intravascular volume depletion may arise.
The etiology of this increased bleeding is unknown, although abdominal trauma and anticoagulation treatments may increase the risk. Nonphysiologic cysts, such as cystadenomas and mature cystic teratomas (dermoid cysts), may, in rare cases, rupture and cause symptoms. In addition to hemorrhage, significant pain can accompany rupture of a dermoid cyst, presumably from spillage of sebaceous fluid, resulting in a diffuse chemical peritonitis.