About this test
A KUB ultrasound looks at both kidneys, the ureters where they can be seen, and the urinary bladder. In men the prostate is also checked, and a post-void residue (PVR) measurement shows how much urine is left after passing urine.
When is it advised?
- Pain in the side or back that may be from a kidney stone
- Blood in the urine, or repeated urine infections
- Difficulty passing urine, a weak stream, or passing urine often at night
- Follow-up after kidney stone treatment
How to prepare
- Come with a full bladder: drink 4–5 glasses of water about an hour before and do not pass urine.
- No fasting is needed for a KUB scan alone.
On the day
- A female staff member (chaperone) is always present during the scan.
- Bring your doctor's prescription or referral slip, a photo ID and any previous reports.
- Most scans take about 10–20 minutes on the table.
- The report is prepared by the radiologist, handed to you and also shared on WhatsApp.
Frequently asked questions
What is PVR?
Post-void residue is the urine left in the bladder right after you pass urine. It is measured by scanning again after you empty your bladder, and helps assess prostate enlargement and bladder emptying.
KUB ultrasound or KUB X-ray — which is better for stones?
They show different things and are often used together. Your doctor will advise which one you need.
This page is general information, not medical advice. Your doctor will decide which test is right for you.