Sonographic appearance of a retained surgical sponge after thyroidectomy: report of three cases.

Although a number of cases of retained surgical sponge (RSS) after thoracic and abdominal surgery have been reported in the literature, the occurrence of RSS after thyroidectomy is very rare. We report the imaging findings of three cases of RSS after thyroidectomy. Sonography of the three patients revealed a hyperechoic mass with marked acoustic shadow. Computed tomography showed a well-defined, circumscribed heterogeneous mass that had gas bubbles inside in two patients, whereas the mass in the third patient was hyperdense and homogenous with smooth margins. All three RSSs were surgically removed.