 [ Symptoms ] what is a renal ultrasound  a renal ultrasound is a video taken of the kidneys using ultrasonic waves a probe placed against the skin reflects high energy sound waves off the kidneys and a computer converts the information into images on a screen [ Disease ] a renal ultrasound is a video taken of the kidneys using ultrasonic waves a probe placed against the skin reflects high energy sound waves off the kidneys and a computer converts the information into images on a screen renal ultrasounds are usually performed to try to find the cause of kidney damage or kidney failure a renal ultrasound may be also done to look for cysts stones masses or other abnormalities of the kidneys even when the kidneys are functioning normally renal ultrasound is a painless and typically risk free test