Renal ultrasound scans, which people may also call kidney ultrasounds, provide an image of the kidneys and may help doctors identify an underlying issue with these organs.

An ultrasound, also known as an ultrasonography or sonography, uses sound waves to generate images of areas inside the body. The procedure is noninvasive, safe, and does not rely on radiation to generate images.

This article explores when a doctor may recommend a kidney ultrasound scan, what to expect before, during, and after the procedure, and the typical next steps.

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A doctor may order a kidney ultrasound to check for any issues of concern within a person’s kidneys and bladder.

An ultrasound can help a doctor check for:

  • injury or damage to the kidneys, such as from an infection
  • the presence of kidney stones, tumors, or cysts
  • irregularities in kidney size and shape
  • blood flow to the kidneys
  • issues with the bladder

According to an older review from 2015, while an ultrasound can help identify masses on the kidney, a doctor may need to follow up the scan with a CT scan to determine if the mass is benign or cancerous.

Another possible use of a kidney ultrasound is for doctors to monitor the status of a kidney transplant. According to a 2022 review, postoperative follow-up using ultrasound kidney scans can help healthcare professionals identify several issues with the new kidneys. These issues include rejection of the transplanted organ and problems with the bladder.

When a doctor needs to take a biopsy of a person’s kidneys, they may use an ultrasound to help guide the biopsy needle. They can then send the sample of kidney tissue to a lab for analysis.

A kidney ultrasound is a minimally invasive procedure that involves very little preparation. The following section discusses what a person may expect before, during, and after the imaging test.


A person typically does not need to do any special preparation for an ultrasound. In most cases, individuals can eat, drink, and take medications as they usually would unless a healthcare professional instructs them otherwise.

In some cases, a medical team member may ask a person to drink about 24 ounces of water before the scan and ask them not to urinate until after the procedure. This helps create a better image of the kidneys and bladder.

A person may want to wear loose, easy to remove clothing for the examination and leave jewelry at home. They may need to roll up their clothing or wear a medical gown before the scan.

For an ultrasound, an individual needs to lay still. Caregivers or parents of children may need to bring along books, toys, or other distractions to help a young child remain still during the procedure.

During the procedure

For an ultrasound, a person will typically lie on an examination table or a reclining exam chair that allows them to lie flat. A healthcare professional will help position them and instruct them on whether they need to roll up any clothing unless they are wearing a medical gown.

Once the person is in position, a healthcare professional will typically place a towel down around any article of clothing that may be close to the gel they will use with the transducer. This device is a handheld probe attached to a computer-sized device with a screen and keyboard. The screen produces an image as the healthcare professional moves the probe around on the person’s abdomen.

The healthcare professional will apply a small amount of gel to the probe before placing it on the abdomen. The gel helps the sound waves the probe creates travel back and forth better.

Throughout the procedure, the healthcare professional will move the probe around the abdomen to different positions and may apply some pressure in different spots. As they do this, the probe sends out sound waves and receives the echo as it bounces off the different structures in the abdomen, such as the kidneys.

At times, the healthcare professional may:

  • hold the transducer still and create marks or notes on the screen
  • take measurements of the kidneys or other structures
  • create a still image of what is on the screen
  • create a small video loop of blood flow, if they are using a Doppler ultrasound

Once the healthcare professional gets the required images or videos, they will wipe the probe and a person’s abdomen clean with a towel. If they are checking the bladder, they may ask a person to empty their bladder and then rescan the area to check how well it has emptied.

The entire procedure typically takes about 30 minutes.

After the procedure

A radiologist will typically examine the ultrasound images or videos following the imaging scans. They will then send a signed report to the ordering doctor, but they may also review the results with the person after the procedure. In most cases, a person’s doctor will discuss the results with them.

Wait times can vary, but a doctor may receive the results of a person’s ultrasound within 1–2 days. The doctor’s office should help schedule a follow-up appointment to review the results.

The kidney ultrasound can help a doctor decide what to do next. They may order a second ultrasound to get different angles or images to help better determine if there are any problems with a person’s kidneys.

They may also order a CT scan, biopsy, or another test to help identify a tumor or other growths.

In some cases, the ultrasound may reveal an issue with the kidneys and allow the doctor to make a diagnosis and begin treatment.

Kidney ultrasound scans can help a doctor see the kidneys to identify possible issues or problems. They may show kidney tumors, cysts, structural problems, blood flow, and bladder problems. Doctors may also use them to help guide a biopsy needle.

The procedure takes roughly 30 minutes and typically requires minimal preparation.

Following a kidney ultrasound, a person may need additional ultrasounds, a biopsy, or other imaging tests. In other cases, a doctor may make a diagnosis and begin treatment for any health conditions affecting someone’s kidneys.