Radiology• Updated 21 October 2026
KUB Ultrasound (Kidneys and Bladder)
An ultrasound of the kidneys, ureters and bladder.
Results: Usually the same day
Quick Summary
Primary Purpose
To look for kidney stones, blockages, cysts and to check how well the bladder empties.
What It Measures
Kidney size, stones, swelling and bladder volume.
Preparation
Drink water so your bladder is full, as instructed.
Overview
KUB ultrasound is a common first test for kidney stones and urinary symptoms.
It can measure urine left in the bladder after passing urine.
What It Measures
Kidneys
Stones, cysts, swelling.
Bladder
Wall, stones and leftover urine.
How It's Performed
- 01
Full bladder
Drink water as advised.
- 02
Scan
Gel and probe on the back and lower tummy.
- 03
Post-void
You may be asked to empty your bladder and be scanned again.
Sources and further reading
Last updated 21 October 2026. For more detail, see these trusted health organisations.
- Ultrasound(opens in a new tab) · MedlinePlus, US National Library of Medicine
- Ultrasound scan(opens in a new tab) · NHS