What can cause an ovarian cyst to rupture?

Nature or injury etc: Most common follicular cysts of menstrual cycle, constantly formed and disappear (rupture) , carpus luteal cysts may be associated with small bleeding, chocolate cysts caused by endometriosis may rupture due to pressure caused by fluid accumulation of fluid, all are harmless, ( may have thin wall ) except tumor cysts, ( same reason) some times direct trauma like car accident may cause.

Like a balloon: An ovarian cyst can rupture when it reaches a certain size, when the wall thins out, when the cyst ages, with change in hormones or with a minor trauma. Many times the rupture is without symptoms, however sometimes it can be very painful, can bleed, can require emergency or urgent health care. Your doc can monitor your cyst with ultrasound and exam.