An endometrioma, commonly called a chocolate cyst, is a cyst that forms on the ovary when endometrial tissue grows on the ovarian surface and bleeds into the developing cyst with each menstrual cycle. On ultrasound, endometriomas have a characteristic appearance: a well-defined, round or oval cyst with homogeneous, low-level internal echoes that give the contents a hazy or ground-glass quality. This distinctive pattern results from the thick, old blood filling the cyst. Endometriomas are often associated with other manifestations of endometriosis and can affect fertility. While their ultrasound appearance is usually distinctive enough for a confident diagnosis, atypical cases may require MRI or surgical evaluation to exclude malignancy.
Sonography Term