A renal ultrasound is a noninvasive exam that produces images, which are used to assess the size, shape and location of the kidneys. An ultrasound may also be used to assess blood flow to the kidneys, according to Johns Hopkins Medicine.
A renal ultrasound procedure is conducted using a transducer that sends out high-frequency sound waves. An ultrasound gel is placed on the transducer and the skin to facilitate smooth movement and the best sound conduction. Johns Hopkins Medicine explains how the transducer is placed on the skin, and the sound waves move through the body. As the sound waves bounce off the organs, they are returned to the transducer for processing. Since the sound waves travel at different speeds depending on the density of the tissue encountered, an image of the organs takes shape, which is then generated by a computer for assessment.
A renal ultrasound can be used to detect a number of potential health problems including cysts, tumors, abscesses, obstructions, fluid collection, infection and kidney stones. The procedure may also be performed to assist in placement of needles for a kidney biopsy or a tube to drain a cyst or abscess. Renal ultrasound may be used after a kidney transplant to ensure the proper functioning of the transplanted kidney, notes Johns Hopkins Medicine.