The homogeneous low-level interval echoes that characterize the commonly encountered cyst may also have a layered appearance. Fluid-debris levels may shift slowly with changes in the patient's position. A complicated cyst may also contain brightly echogenic foci that scintillate as they shift. If aspirated, the cyst fluid may be a clear, yellow or turbid green color. The term "COMPLICATED" describes the ultrasound appearance and does not indicate that pus or blood is responsible for the internal echoes. Complicated cysts do not contain solid mural nodules. A discrete solid component places the cystic lesion into the category of COMPLEX MASS, requiring aspiration or other intervention.