You must be fasting 6 to 8 hours before your test. Below is some information regarding your test.


  • To detect a mass, cyst, kidney stone, or other obstruction in the kidney.
  • To determine kidney size and shape.
  • To locate the kidney during a kidney biopsy.
  • To determine circulation in the renal arteries and veins by the use of a Doppler monitor. This variation does not alter the test from the patient’s standpoint but yields additional information.

How it works:

A transducer passed over your kidneys emits sound waves that, like sonar, bounce off your kidney, transmitting a picture of the organ that can be displayed on a video screen.


  • You will need to fast 6 to 8 hours before your ultrasound (water is permitted).
  • You disrobe and don a hospital gown.
  • A water-soluble gel is applied to the skin on your torso as a medium for the transducer (see below).

Test procedure:

  • You lie on an examining table while a transducer, a handheld unit that emits sound waves, is passed over the skin above your kidneys.
  • A video screen shows the images, which are assessed or photographed for later assessment.