Ovarian cyst rupture refers to the expulsion of the fluid inside an ovarian cyst out of the cyst due to external forces. When an ovarian cyst ruptures, the patient can suddenly experience severe pain in the lower abdomen on one side, which is often unbearable. At the same time, symptoms such as nausea and vomiting may accompany the pain. If the fluid inside the cyst is irritating, for example, the fluid in an endometriosis cyst which resembles chocolate, this fluid can promote widespread abdominal pain. This irritation can lead to peritonitis. Generally, an ovarian cyst rupture requires immediate surgical intervention for treatment.