A Kidney Ultrasound — often referred to as a renal ultrasound — is an imaging test that examines the kidneys and bladder. It uses sound waves to create real-time images of your organs, which your healthcare provider views on a screen. The sound waves are harmless and undetectable to your ears, and the procedure is straightforward, usually lasting between 20 and 30 minutes.
A Kidney Ultrasound uses a transducer — a flat-ended, microphone-shaped device — moved over your kidneys and bladder to relay real-time images to a connected screen. You may feel some pressure when the wand is applied, but the procedure is painless. The images are then analysed to provide a diagnosis and help your doctor create a treatment plan.
A doctor will suggest a Kidney Ultrasound when more information is needed about the cause of a kidney problem. As kidney and bladder issues can be connected, the ultrasound often includes images of both organs. A Kidney Ultrasound may be requested if your doctor suspects any of the following: an abscess; a blockage or obstruction; injury or trauma; issues with blood flow to the kidneys; irregularities with the shape or size of the kidneys; kidney disease; kidney infection; kidney stones; kidney cysts; kidney tumour; or urine building up in the kidney (hydronephrosis).
An ultrasound is also used to guide a kidney biopsy or to check on the health of a transplanted kidney.
In most cases, no specific preparation is required — you can eat and drink as normal on the day of your test. In some cases, you may be asked to avoid eating after midnight the night before. Your doctor will advise if any fasting is required.
Your healthcare provider may also request a post-void residual urine test (PVR), in which case you will be asked to drink 30 to 32 ounces of water an hour before the ultrasound and not empty your bladder until after the test. This is to evaluate your bladder's capacity and function. Arriving with a full bladder is becoming more common for kidney ultrasounds, but unless your doctor specifies this, no special bladder preparation is needed.
Step 1 — Change
On arrival, you will be provided with a hospital gown to change into. Wearing loose-fitting, comfortable clothing makes this process quicker. Once changed, you will lie on a padded exam table, and the technician will help you get into the correct position if needed.
Step 2 — Gel
A water-soluble gel will be applied to your skin where the transducer will be placed. The gel is painless and will not stain your clothing, though it may feel cool on first contact.
Step 3 — The scan
A radiologist will place the transducer on your abdomen and move it slowly, applying gentle pressure. Most people find the process painless, though if the area is tender you may feel some of the pressure. The radiologist will take images and short videos on the connected screen. You may be asked to roll onto your side or hold your breath to capture clearer images from different angles. You may also be asked to empty your bladder partway through the scan so that images can be taken in both full and empty states — a nearby bathroom will be available.
Step 4 — Images are reviewed
After the scan, images are reviewed by a radiologist, who may discuss their findings with you directly or write a report to be shared with your healthcare provider.
After your scan, you can remove the gel, change your clothing, and resume your usual activities. You can eat and drink normally, and most people are able to return to work immediately. Results are typically provided within 24 to 48 hours, after which your healthcare provider will contact you to discuss the findings by phone or at a follow-up appointment.
A dark spot on a kidney ultrasound appears where sound waves have hit liquid or a non-solid material rather than bouncing back. This can indicate an abscess or cyst, and additional imaging may be required to examine the area more closely and reach a diagnosis. At this stage, your doctor will not be able to confirm whether the finding is benign or something more serious — there is no need to panic, as this can often be a minor issue.
Fast and informative
Kidney ultrasounds provide a clear picture of your kidneys, revealing tumours, blockages, and infections quickly, allowing doctors to act promptly.
Painless and non-invasive
The scan causes minimal disruption to your day and requires no invasive procedures.
No radiation exposure
Ultrasound is extremely safe, using no radiation, and provides radiologists with clear images of soft tissue that does not show up on X-rays.
First-line diagnostic tool
A Kidney Ultrasound can identify a variety of kidney disorders without the need for an X-ray or biopsy, and is considered the reliable first step in diagnosing kidney issues.
There are no known risks associated with a Kidney Ultrasound. In rare cases, human error in moving the wand or reading the images may result in inaccurate findings. Blockages may also occasionally prevent sound waves from penetrating the body effectively. These situations are uncommon and, as a Kidney Ultrasound is a first-line test, any inaccuracies will generally be identified at the next stage of diagnosis. You can always request a second scan or a second opinion if you are not satisfied with the findings.
You should contact your healthcare provider if you have questions about how to prepare for your Kidney Ultrasound, what to expect during the procedure, or when to expect your results. They can also help relieve any concerns you may have beforehand. Contact them too if you have not received your results within the expected timeframe, or to arrange a follow-up appointment.
A Kidney Ultrasound is a quick, non-invasive test that provides clear images of your kidneys and bladder. It is often used as the first step in diagnosing kidney problems and forming a treatment plan. The safe procedure requires little preparation, and you can continue with your day immediately afterwards.