A renal ultrasound is a non-invasive imaging exam that assesses the shape, size and structure of the kidneys, essential for diagnosing and monitoring urological conditions such as kidney stones, infections or structural changes in the urinary tract.
Who should have this exam?
A renal ultrasound is recommended whenever there are symptoms or risk factors related to the urinary system, namely:
- ✓People with lower back or flank pain, possibly associated with kidney stones
- ✓Cases of blood in the urine (hematuria), visible or detected on lab tests
- ✓Suspected or ongoing monitoring of recurring urinary infections
- ✓Changes found in blood or urine tests, such as abnormal kidney function values
- ✓Monitoring of kidney cysts or other previously identified changes
- ✓Assessment of high blood pressure of unclear cause
- ✓Preventive screening for people with a family history of kidney disease
Because it is quick, safe and radiation-free, a renal ultrasound is often the first imaging exam requested when urinary symptoms occur, before moving on to more complex investigations.
How is the renal ultrasound performed?
The exam is performed transabdominally, with the patient lying down, using a conductive gel applied to the skin and an ultrasound probe moved over the lower back and abdominal area. High-frequency sound waves create real-time images of the kidneys and surrounding structures.
Depending on the clinical indication, the exam may be extended to include the ureters and bladder, forming a more complete urological ultrasound. The procedure requires no anesthesia and no invasive preparation.
How should I prepare for the exam?
Preparation for a renal ultrasound is simple and non-invasive.
Normal hydration
Fasting is not required. You can keep your usual diet and fluid intake before the exam.
Comfortably full bladder
If the bladder is also being assessed, it is recommended to drink water about an hour before and avoid urinating until the exam.
Comfortable clothing
Wear clothing that is easy to partially remove, since the abdominal and lower back area needs to be exposed.
What is assessed during a renal ultrasound
Shape, size and location of the kidneys
Checks whether both kidneys have dimensions and contours within expected parameters.
Presence of kidney stones
Identifies the presence, location and approximate size of any stones in the kidneys.
Dilation of the collecting system
Detects signs of hydronephrosis, a dilation that may indicate obstruction of urine flow.
Presence of cysts or masses
Assesses the presence of cystic formations or other lesions that may require further investigation.
Renal cortex thickness
A relevant indicator of the function and overall health of the kidney tissue.
Bladder and ureters (when assessed)
Checks bladder emptying, bladder wall thickness, and indirect signs of ureteral dilation.
Benefits of renal ultrasound
Early detection
Identifies stones, cysts or structural changes before they become symptomatic or more serious.
Radiation-free
Unlike CT scans, it does not expose the patient to radiation, and can be repeated whenever needed.
Supports diagnosis
Provides objective information that guides the doctor's decisions on further tests or treatment.
Monitoring over time
Allows tracking the progression of cysts, stones or other previously identified conditions.
Common questions about renal ultrasound
Does a renal ultrasound hurt?+
No. It is a painless, non-invasive exam. You may feel slight pressure from the probe on your skin, but no significant discomfort.
Do I need to have a full bladder?+
Yes, when the bladder is also being assessed. It is recommended to drink water about an hour before the exam and avoid urinating until the ultrasound, to allow for a more complete assessment.
What is the difference between a renal ultrasound and a full urological ultrasound?+
A renal ultrasound focuses specifically on the kidneys, while a urological ultrasound may also include the ureters, the bladder and, in men, an initial assessment of the prostate via the abdominal approach.
How long does the exam take?+
Usually between 15 and 20 minutes, which can vary depending on the patient's anatomy and the need for additional measurements.
Do I need a medical referral to book this exam?+
No referral is required. The exam can be requested directly during a urology or general practice appointment, or booked independently at Aeger Prima.
Book your renal ultrasound
A quick, painless exam with no radiation, with results discussed at a dedicated urology appointment.
