Implants on the ovary can cause endometriomas, called chocolate cysts because of their thick, brown fluid from accumulated old blood.  Endometriomas typically appear as a unilocular adnexal mass with homogeneous, low level echoes (ie, blood).  Patients with symptomatic endometriomas require surgical resection (eg, cystectomy) to improve pain symptoms, improve fertility, and decrease the risk of ovarian torsion.

Ultrasonography demonstrates a homogenous cyst with internal echoes (eg, "ground glass")

With ground glass appearance