Clinical Presentation

A child with right flank pain and hematuria.

A longitudinal sonogram of the right kidney demonstrates an echogenic focus in the inferior portion of the collecting system with acoustic shadowing (arrow). There is no evidence of urinary obstruction.

Differential Diagnosis

• Nephrolithiasis: Kidney stones, like stones elsewhere in the body, typically appear echogenic and cast acoustic shadows on sonography.

• Blood clot: Hematomas may appear hyperechoic, but they generally do not cast acoustic shadows. They are typically associated with bleeding diatheses, recent trauma or surgery, or tumors or stones.

• Fungus ball: