In this article, we explore the causes, symptoms, and treatments of chocolate cysts. We also look at the ways that these cysts and endometriosis can affect fertility. Get medically verified details on chocolate cyst causes, symptoms, diagnosis methods, and treatment options available in India. Learn about ovarian endometriomas, cysts filled with old blood that are a sign of endometriosis. Find out the symptoms, causes, complications, diagnosis and treatment options for this condition. An endometrioma (commonly known as a chocolate cyst) is a type of cyst that forms when endometriosis affects the ovaries. They develop deep within the ovaries and are filled with old blood and endometrial-like tissue, giving them their characteristic dark, chocolate-like appearance.