Renal ultrasound (kidney ultrasound) is a safe, noninvasive imaging test that uses sound waves to create images of your kidneys and bladder. It helps healthcare providers detect kidney stones, tumors, infections, damage, and structural abnormalities.
Due to the test’s safety and wide availability, it’s often the first imaging procedure healthcare providers use to assess kidney health.
Your healthcare provider may recommend a renal ultrasound if you have signs or symptoms that may be related to your kidney anatomy or function, such as proteins in your urine, nausea, appetite loss, or swelling in your hands and feet.
A renal ultrasound can help detect:
- Abnormalities in the size or location of your kidneys
- Signs of injury or damage to your kidneys
- Blood flow to the kidneys
- Presence of kidney stones, cysts, or tumors
- How your bladder empties
Your healthcare provider may also use renal ultrasound to help guide the needle during a kidney biopsy, which involves taking a small tissue sample.
Your healthcare provider may give you instructions for how to prepare for the procedure. They may cover topics such as:
- Food and drink: You may need to fast (avoiding eating or drinking anything) for a few hours before the test. Sometimes, you may need to drink 24 ounces (three glasses) of water before the procedure to help create clearer images. Discuss with your healthcare provider their recommendations.
- Bathroom use: It may help if your bladder is full, so your healthcare provider may ask you to refrain from urinating that day until after the imaging test is done.
- What to wear: Wear comfortable clothes you can easily remove or adjust. In some cases, you may need to put on a hospital gown for the procedure.
You will also typically need to consult your insurance provider, if you have one, to understand whether they will cover the costs of the ultrasound.
Ultrasound imaging uses a small handheld device, called a transducer, that emits sound waves. The sound waves travel through your body and bounce back to the transducer from your organs. A computer then uses these sound waves to create images of your kidneys.
During the Test
Before undergoing a renal ultrasound, you may need to change into a hospital gown or otherwise expose the skin near your kidneys. The sonographer, a technologist specially trained to perform ultrasound, will then ask you to lie down on an exam table.
Then, they will apply a water-based gel to the area of skin near the kidney or kidneys they’re examining. This gel helps ensure good contact between the transducer and your skin.
The sonographer moves the transducer back and forth over that area, sending sound waves through your skin to the internal organs. A computer measures the sound waves that bounce back from your organs and creates images of your kidneys. The sonographer may ask you to hold your breath to help them get better images.
The entire procedure takes about 30 minutes to complete. In most cases, you won’t experience any discomfort unless the area is already tender.
After the Test
A renal ultrasound doesn’t require any recovery time. You can typically leave the hospital or clinic after a renal ultrasound and return to your daily activities.
A radiologist, a doctor specializing in interpreting the results of imaging procedures, typically reviews your ultrasound images and gives the results to your healthcare provider.
Ultrasounds are generally quite safe, with no significant side effects. Unlike X-rays, ultrasounds do not use ionizing radiation and are not associated with radiation exposure.
In rare cases, an ultrasound may interfere with tissues and fluids in your body. Ultrasound waves may heat body tissues and produce small pockets of gas in body fluids or tissues. Experts are not yet sure of the long-term effects. Healthcare providers recommend undergoing an ultrasound only when necessary.
The results of renal ultrasound are usually available within a day or two of the test. You can expect your healthcare provider to review the findings with you and discuss any next steps. Based on the findings, they may recommend treatment or additional tests, such as a kidney biopsy.
If you have a condition that your healthcare provider is treating, they may also recommend scheduling follow-up visits to monitor your health and assess whether your treatment is working.
Renal ultrasound is a procedure that helps assess the health, structure, and function of your kidneys and bladder. It’s a quick procedure that a specially trained healthcare provider may perform in a clinic or hospital. This type of imaging procedure is also safe and non-invasive, using sound wave technology to create computerized images of your internal organs.
