A kidney ultrasound is a noninvasive diagnostic examination that produces images, which are used to assess the size, shape, location of the kidneys and related structures, such as the ureters and bladder. Ultrasound may also be used to assess blood flow to the kidneys. It can detect cysts, tumors, abscesses, obstructions, fluid collection, calculi (stones), infection etc within or around the kidneys. It may be also used after a kidney transplant to evaluate the transplanted kidney.