What is a kidney ultrasound?
A kidney ultrasound is an imaging test that uses sound waves to look at your kidneys. It can check the size, shape, and location of your kidneys. It also lets your healthcare provider see how well blood is flowing in your kidneys.
The healthcare provider uses a device called a transducer to make the images of your kidneys. The transducer sends out sound waves that bounce off your kidneys. The sound waves are too high-pitched for you to hear. The transducer then picks up the bounced sound waves. These are made into pictures of your kidneys.
Your provider can add another device called a Doppler probe to the transducer. This probe lets your provider hear the sound waves the transducer sends out. He or she can hear how fast blood is flowing through a blood vessel and in which direction it is flowing. No sound or a faint sound may mean that you have a blockage in the flow.
Ultrasound is safe to have during pregnancy because it does not use radiation. It is also safe for people who are allergic to contrast dye because it does not use dye.
Why might I need a kidney ultrasound?
You may need a kidney ultrasound if your healthcare provider thinks you may have a problem in your kidneys. These problems include:
- Collection of fluid
- Kidney stone
You may also have a kidney ultrasound to help:
- Put a needle in place to take a tissue sample from the kidneys (biopsy)
- Drain fluid from a cyst or abscess
- Put a drainage tube in place
- See how blood is flowing to the kidneys through the renal arteries and veins
Your provider may also use a kidney ultrasound after a kidney transplant to see how well the transplanted kidney is working.
Your healthcare provider may have other reasons to recommend a kidney ultrasound.
What are the risks of a kidney ultrasound?
A chest ultrasound has no risk from radiation. Most people have no discomfort from the transducer moving across the skin.
You may have risks depending on your specific health condition. Be sure to talk with your provider about any concerns you have before the procedure.
Certain things can make a kidney ultrasound less accurate. These include:
- Severe obesity
- Barium in your intestines from a recent barium test
- Intestinal gas
How do I get ready for a kidney ultrasound?
- Your healthcare provider will explain the procedure to you. Ask him or her any questions you have about the procedure.
- You may be asked to sign a consent form that gives permission to do the test. Read the form carefully and ask questions if anything is not clear.
- You usually do not need to stop eating or drinking before the test. You also usually will not need medicine to help you relax (sedation).
- The gel put on your skin during the test does not stain clothing, but you may want to older clothing. The gel may not be completely removed from your skin afterward.
- You should not empty your bladder before the test if the healthcare provider is going to look at the bladder.
- Follow any other instructions your provider gives you to get ready.
What happens during a kidney ultrasound?
You may have a kidney ultrasound as an outpatient or as part of your stay in a hospital. The way the test is done may vary depending on your condition and your healthcare provider's practices.
Generally, a kidney ultrasound follows this process:
- You will be asked to remove any clothing, jewelry, or other objects that may get in the way of the scan.
- You may be asked to remove clothing. If so, you will be given a gown to wear.
- You will lie on an exam table on your stomach.
- The technologist will put a clear gel on the skin over the area to be looked at.
- The technologist will press the transducer against the skin and move it over the area being studied.
- If blood flow is being looked at, you may hear a "whoosh, whoosh" sound when the Doppler probe is used.
- If your bladder is looked at, you will be asked to empty your bladder after scans of the full bladder are done. You will have more scans done of the empty bladder.
- Once the test is done, the technologist will wipe off the gel.
A kidney ultrasound is not painful. But you may have some discomfort from having to remain still during the test. The gel will also feel cool and wet. The technologist will use all possible comfort measures and do the scan as quickly as possible to minimize any discomfort.
What happens after a kidney ultrasound?
You do not need any special care after a kidney ultrasound. You may go back to your usual diet and activities unless your healthcare provider tells you otherwise.
Your healthcare provider may give you other instructions, depending on your situation.
Before you agree to the test or the procedure make sure you know:
- The name of the test or procedure
- The reason you are having the test or procedure
- The risks and benefits of the test or procedure
- When and where you are to have the test or procedure and who will do it
- When and how will you get the results
- How much will you have to pay for the test or procedure