A chocolate cyst, medically known as an endometrioma, is an ovarian cyst that forms when endometrial tissue, the type that normally lines the uterus, grows on or within the ovary and bleeds with each menstrual cycle. Over time, the trapped blood accumulates and becomes thick and dark brown, resembling melted chocolate, which gives the cyst its informal name. On ultrasound, an endometrioma has a characteristic appearance: a well-defined cyst with homogeneous, low-level internal echoes giving it a ground-glass or hazy appearance. This pattern is distinctive enough that an experienced sonographer can often suggest the diagnosis with high confidence, though complex or atypical cases may require MRI or surgical evaluation for confirmation.
Sonography Term