Also called a renal ultrasound, a kidney ultrasound is a noninvasive exam that uses ultrasound waves to produce images of your kidneys.

These images can help your doctor evaluate the location, size, and shape of your kidneys as well as blood flow to your kidneys. A kidney ultrasound usually includes your bladder, too.

Ultrasound, or sonography, uses high-frequency sound waves sent out by a transducer pressed against your skin. The sound waves move through your body, bouncing off organs back to the transducer.

These echoes are recorded and digitally turned into video or images of the tissues and organs selected for examination.

Ultrasound isn’t hazardous and there are no known harmful side effects. Unlike X-ray tests, ultrasound doesn’t use radiation.

Your doctor may recommend a kidney ultrasound if they think you have a kidney problem and they need more information. Your doctor might be concerned about:

Other reasons you might need a kidney ultrasound include:

  • guiding your doctor to insert a needle for a tissue biopsy of your kidney
  • draining fluid from a kidney abscess or cyst
  • helping your doctor place a drainage tube into your kidney

If your doctor orders a kidney ultrasound, they’ll have instructions about how to prepare and what to expect. Typically, this information includes:

  • drinking 3 eight-ounce glasses of water at least one hour before the exam and not emptying your bladder
  • signing a consent form
  • removing clothing and jewelry since you’ll likely be given a medical gown
  • lying facedown on an exam table
  • having a conductive gel applied to your skin in the area being examined
  • having the transducer rubbed against the area being examined

You might be a little uncomfortable lying on the table and the gel and transducer might feel cold, but the procedure is noninvasive and painless.

Once the procedure is done, the technician will forward the results to your doctor. They’ll review them with you during an appointment that you can make the same time you make the ultrasound appointment.

A kidney ultrasound is a noninvasive, painless medical procedure that can give your doctor needed details to properly diagnose a suspected kidney problem. With that information, your doctor can customize a treatment plan to help your condition and your symptoms.