Endometriosis is the growth of endometrial tissue outside the uterus. Endometrial tissue is normally found of the inside of the uterus, but can travel to other locations. The ovary, because of its proximity to the uterus, is one of the most common locations for endometriosis. As endometriosis grows into the ovary, a mass filled with old blood and tissue develops, called a chocolate cyst, or, more formally, an endometrioma. Endometriomas grow slowly and can cause pain and problems with fertility, since the ovary can no longer function normally. Cyst rupture causes potentially severe symptoms and usually requires surgery.
Ruptured endometriomas cause acute abdominal pain--pain that starts suddenly and can be severe. Pain doesn't come from the rupture of the cyst, but from the blood and debris inside the cyst irritating the peritoneum, the lining of the abdominal cavity. The release of this material causes chemical peritonitis. Chemical peritonitis is not caused by infection, but by inflammation of the tissues of the peritoneum. The entire abdominal may also be tender to touch.
Inflammation in the peritoneal cavity after an endometrioma ruptures can cause fever, lead author Barbara Levy, M.D. states on UpToDate. Symptoms of shock, such as pallor, sweatiness, rapid heartbeat, confusion and weakness, may also develop, but dizziness and low blood pressure don't develop unless there is significant blood loss, which generally doesn't occur, Jonathan Berek and Emil Novak report in their 2007 textbook "Berek and Novak's Gynecology."
Rigidity and guarding of the abdomen--a reluctance to have the abdomen palpated--may develop from chemical peritonitis. Bowel sounds may decrease due to slowing of intestinal activity, the abdomen may become distended, and vomiting may also occur, William Silen states in his textbook, "Cope's Early Diagnosis of the Acute Abdomen."