A HIDA scan (hepatobiliary scan) is a nuclear medicine test that shows how your gallbladder and bile ducts are working. A small radioactive tracer is injected and followed as it moves from the liver through the bile system — revealing blockages or a gallbladder that isn't emptying properly. It's used when an ultrasound (the usual first test for gallstones) can't fully explain the problem. It's painless and uses a small radiation dose.
Key takeaways
- A HIDA scan shows how the gallbladder and bile ducts are functioning.
- A tracer is followed from the liver through the bile system.
- It reveals blockages or a gallbladder that isn't emptying properly.
- It's used when ultrasound can't fully explain gallbladder symptoms.
Most gallbladder problems start with an ultrasound, which is excellent at finding gallstones. But sometimes the gallbladder looks fine yet still causes pain — and that’s where a HIDA scan comes in.
What a HIDA scan shows
A HIDA scan (also called a hepatobiliary or cholescintigraphy scan) is a nuclear medicine test that shows how your gallbladder and bile ducts are working, rather than just what they look like.[1] A small radioactive tracer is injected into a vein; the liver takes it up and passes it into the bile, and a gamma camera follows it as it flows from the liver → bile ducts → gallbladder → small intestine.
By watching that journey, doctors can see:[1]
- a blockage in a bile duct (the tracer can’t get through);
- a gallbladder that isn’t filling or emptying properly;
- bile leaks after surgery.
Where it fits
An ultrasound is the usual first test for gallbladder pain and is best for spotting stones.[2] A HIDA scan is added when the ultrasound is normal or unclear but symptoms continue — because it measures function, which ultrasound can’t. Sometimes a medication is given during the scan to make the gallbladder squeeze, measuring how well it empties (the “ejection fraction”).
What to expect
You may be asked to fast beforehand. The tracer is injected, then the camera takes pictures over 1–2 hours as the tracer moves through the system — so it’s a longer scan, but painless.[2] The radiation dose is small, and the tracer clears over the following day. Tell the team if you are, or might be, pregnant or breastfeeding.
For the first-line test, see our guide to imaging for gallstones.
Frequently asked questions
What is a HIDA scan used for?
To check how the gallbladder and bile ducts are functioning — finding blockages, poor gallbladder emptying, or bile leaks — usually after an ultrasound.[1]
How is a HIDA scan different from an ultrasound?
Ultrasound shows the structure (and stones); a HIDA scan shows function (how bile flows and how well the gallbladder empties). They answer different questions.[2]
Why does a HIDA scan take so long?
Because it follows the tracer’s journey through the bile system in real time, which takes 1–2 hours. It’s painless — you can rest during the imaging.[2]
Sources
- RadiologyInfo.org (RSNA & ACR) — General Nuclear Medicine — www.radiologyinfo.org/en/info/gennuclear
- RANZCR / InsideRadiology — Nuclear medicine (Cain) — www.insideradiology.com.au/nuclear-medicine/
