Which scan for gallstones? Ultrasound first

Gallstones are common, and when they cause pain (typically in the upper-right abdomen), imaging is how they’re confirmed. One test does most of the work.

Ultrasound — the first and usual test

An abdominal ultrasound is the main test for suspected gallstones.^[1] It uses no radiation, is quick, and is highly accurate at finding stones in the gallbladder. It also shows:^[2]

• the gallbladder wall (thickening can signal inflammation — cholecystitis);
• the bile ducts (widening can suggest a blockage);
• nearby organs like the liver.

You’ll usually be asked to fast for several hours beforehand, so the gallbladder is full and easier to see. It’s painless — gel and a probe over your upper abdomen.

When another scan is added

Ultrasound is often the only scan needed. But sometimes the picture is incomplete:^[2]

• MRCP — a special MRI of the bile ducts (no radiation, no contrast injection needed) used when a stone in a duct is suspected but not clearly seen.
• HIDA scan — a nuclear medicine function test, used when the gallbladder looks normal but symptoms continue (see our HIDA scan guide).
• CT — mainly for complications or when the diagnosis is uncertain, not for routine stone detection.

In Australia

An ultrasound for gallbladder symptoms needs a referral and usually attracts a Medicare rebate; many clinics bulk bill. For what the scan is like, see our guides to abdominal ultrasound and ultrasound preparation.

Frequently asked questions

What’s the best scan for gallstones?

An abdominal ultrasound — it’s radiation-free, quick and highly accurate for gallstones, which is why it’s the first test.^[1]

Do I need a CT for gallstones?

Usually not — ultrasound is better for detecting stones. CT is mainly used if a complication is suspected or the diagnosis is unclear.^[2]

Why do I have to fast before a gallbladder ultrasound?

Fasting keeps the gallbladder full, which makes stones and the gallbladder wall much easier to see.^[1]