Kidney ultrasound (renal scan) Diagnostic Imaging

A kidney ultrasound uses sound waves to create live images of your kidneys and nearby structures, often including the bladder.

Kidney ultrasound (renal scan) procedure illustration

Overview

A kidney ultrasound uses sound waves to create live images of your kidneys and nearby structures, often including the bladder. It does not use radiation. A technologist moves a small handheld probe over your abdomen and sides with a layer of gel to help send and receive sound waves. This test helps check kidney size and shape, fluid around the kidney, blockages, stones, cysts, masses, and blood flow (with Doppler). Some people use the term renal ultrasound. The phrase renal scan can also mean a nuclear medicine test that uses a small amount of radioactive tracer; that is a different exam.

Overview Preparation Clinical Info Recovery FAQ References

Also known as: Renal ultrasound, Kidney sonogram, Renal US

Recovery
Same day
Return to Work
Same day

Preparation & Next Steps

Everything you need to know before and after your procedure

Before Care

  • Review any instructions from the imaging center about drinking water or fasting; some exams require a full bladder or short fasting period
  • Bring a photo ID, insurance information, and the imaging order or referral
  • Wear comfortable, loose clothing; you may be asked to change into a gown
  • Remove jewelry or accessories that could be in the scan area
  • Bring prior imaging reports or discs if available to help comparison
  • Plan for about 30–60 minutes on site, including check-in and positioning
  • Confirm accessibility needs or language services with the facility in advance
  • Ask the clinic how and when you will receive your report and images

After Care

  • Wipe off any remaining gel and resume normal eating, drinking, and activities
  • You may use the restroom after the exam if you were asked to arrive with a full bladder
  • Review how results will be shared; reports are typically sent to the ordering clinician
  • Keep a copy of your report and images for your records when available
  • If more imaging or labs are suggested, note scheduling and preparation needs
  • Contact your clinician if your symptoms change or worsen after the exam
  • Verify insurance coverage for any follow-up tests to avoid unexpected bills

Clinical Information

Important medical details about this procedure

Indications

  • Flank or back pain possibly related to the kidneys
  • Blood in the urine (hematuria)
  • Frequent or complicated urinary tract infections
  • Abnormal kidney blood or urine tests
  • Known kidney cysts or masses that need monitoring
  • Suspected kidney stones or blockage (hydronephrosis)
  • High blood pressure possibly related to kidney disease
  • Monitoring after kidney transplant

Alternatives

  • CT scan of the abdomen and pelvis or CT urogram
  • MRI or MR urography
  • Nuclear medicine renal scan (renogram) to assess function and drainage
  • Plain abdominal X-ray (limited for stones)
  • Urinalysis and blood tests as part of evaluation
  • Point-of-care ultrasound in a clinic or emergency setting

Risks

  • No ionizing radiation exposure
  • Temporary discomfort from probe pressure
  • Skin irritation from gel is rare
  • Limited views in people with bowel gas, dressings, or larger body size
  • May miss very small stones or early disease, leading to additional tests

Contraindications

  • Few true contraindications for standard ultrasound
  • Open wounds, burns, or bulky dressings over the scan area
  • Inability to lie still or follow simple breathing instructions

Recovery Timeline

What to expect during your recovery

Most people return to normal activities right after a kidney ultrasound. There is no medical recovery period for a standard exam.

Typical Range

Same day

Return to Work

Same day

Recovery Milestones

Day 0

Resume usual daily activities and diet

Day 0–2

Review how results will be delivered (portal, phone, or follow-up visit)

Frequently Asked Questions

Common questions and expert answers about this procedure

What does a kidney ultrasound show?

It shows kidney size, shape, and structure. It can help detect cysts, masses, stones, swelling from blockage, and fluid around the kidney. The bladder is often included.

How is the test done?

A technologist applies warm gel and moves a handheld probe over your abdomen and sides while capturing images. You may be asked to change position or briefly hold your breath.

Do I need to fast or have a full bladder?

Instructions vary by facility and whether the bladder is included. Some centers ask for a full bladder or short fasting. Follow the directions provided with your appointment.

Is there radiation or contrast?

No ionizing radiation is used. Contrast is not typically used for standard kidney ultrasound. Some centers may use Doppler settings to assess blood flow.

How long does it take?

The scan itself is often 15–30 minutes. With check-in and positioning, plan for about 30–60 minutes total.

Will it hurt?

It is generally painless. You might feel mild pressure from the probe, especially over tender areas.

How does a renal ultrasound differ from a renal scan?

Ultrasound uses sound waves to show anatomy. A nuclear medicine renal scan uses a small amount of radioactive tracer to assess kidney function and drainage.

When will I get results?

A radiologist reviews the images and sends a report to the ordering clinician. Many centers share results through a patient portal or at a follow-up visit.