Ultrasound has a lower sensitivity (24-77%) when compared to CT (96%). Specificity for both techniques approaches 100%.

Ultrasound is often used as the first line imaging technique in pregnant women and children where radiation is best avoided.

Calculi as small as 0.5 mm can be visualised but sensitivity increases with stone size. Visualisation of ureteral jets within the bladder lumen on ultrasound disappears with obstruction and may indicate the presence of ureteral obstruction. Twinkling artefact on Doppler may aid the diagnosis of smaller stones. Magnetic resonance imaging (MRI) has limited usefulness in detecting calculi.

The ultrasound is showing a renal stone.

Click on the ultrasound to enlarge.

POCUS – Point of Care Ultra Sound

Emergency physicians are now gaining experience in the use of bedside ultrasound to detect an abdominal aorta aneurysm (AAA) at the earliest clinical opportunity. It is recommended good practice to exclude AAA in patients aged >60 years in whom renal colic is suspected. If a normal sized aorta is seen on US along its full extent then an aortic aneurysm can be excluded.