A hepatobiliary iminodiacetic acid (HIDA) scan is an imaging procedure used to diagnose problems of the liver, gallbladder and bile ducts.
For a HIDA scan, also known as cholescintigraphy or hepatobiliary scintigraphy, a radioactive tracer is injected into a vein in your arm. The tracer travels through your bloodstream to your liver, where the bile-producing cells take it up. The tracer then travels with the bile into your gallbladder and through your bile ducts to your small intestine.
A nuclear medicine scanner (gamma camera) tracks the flow of the tracer from your liver into your gallbladder and small intestine and creates computer images.
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Why it's done
Gallbladder and bile duct
The gallbladder serves as a reservoir for a yellow-green fluid produced in your liver (bile). Bile flows from your liver into your gallbladder, where it's held until needed during the digestion of food. When you eat, your gallbladder releases bile into the bile duct, where it's carried to the upper part of the small intestine (duodenum) to help break down fat in food.
A HIDA scan is most often done to evaluate your gallbladder. It's also used to look at the bile-excreting function of your liver and to track the flow of bile from your liver into your small intestine. A HIDA scan is often used with X-ray and ultrasound.
A HIDA scan might help in the diagnosis of several diseases and conditions, such as:
- Gallbladder inflammation (cholecystitis)
- Bile duct obstruction
- Congenital abnormalities in the bile ducts, such as biliary atresia
- Postoperative complications, such as bile leaks and fistulas
- Assessment of liver transplant
Your doctor might use a HIDA scan as part of a test to measure the rate at which bile is released from your gallbladder (gallbladder ejection fraction).
A HIDA scan carries only a few risks. They include:
- Allergic reaction to medications containing radioactive tracers used for the scan
- Bruising at the injection site
- Radiation exposure, which is small
Tell your doctor if there's a chance you could be pregnant or if you're breastfeeding. In most cases, nuclear medicine tests, such as the HIDA scan, aren't performed in pregnant women because of potential harm to the baby.
How you prepare
Food and medications
Your doctor is likely to ask you:
- To fast for four hours before your HIDA scan. You might be allowed to drink clear liquids.
- About medications and supplements you take.
Clothing and personal items
You might be asked to:
- Change into a hospital gown
- Leave jewelry and other metal accessories at home or remove them before the procedure
What you can expect
Before the procedure
Your health care team will position you on a table, usually on your back, and inject the radioactive tracer into a vein in your arm. You might feel pressure or a cold sensation while the radioactive tracer is injected.
During the procedure
During the test, you may get an intravenous injection of the drug sincalide (Kinevac), which makes your gallbladder contract and empty. Morphine, another drug sometimes given during a HIDA scan, makes the gallbladder easier to visualize.
A gamma camera is positioned over your abdomen to take pictures of the tracer as it moves through your body. This process takes about an hour, during which you'll need to remain still.
Tell your team if you become uncomfortable. You might be able to lessen the discomfort by taking deep breaths.
On a computer, the radiologist will watch the progress of the radioactive tracer through your body. In some cases, you might need additional imaging within 24 hours if original images aren't satisfactory.
After the procedure
In most cases, you can go about your day after your scan. The small amount of radioactive tracer will lose its reactivity or pass through your urine and stool over the next day or two. Drink plenty of water to help flush it out of your system.
To make a diagnosis, your doctor will consider your signs and symptoms and other test results with the results of your HIDA scan.
Results of a HIDA scan include:
- Normal. The radioactive tracer moved freely with the bile from your liver into your gallbladder and small intestine.
- Slow movement of radioactive tracer. Slow movement of the tracer might indicate a blockage or obstruction, or a problem in liver function.
- No radioactive tracer seen in the gallbladder. Inability to see the radioactive tracer in your gallbladder might indicate acute inflammation (acute cholecystitis).
- Abnormally low gallbladder ejection fraction. The amount of tracer leaving your gallbladder is low after you've been given a drug to make it empty, which might indicate chronic inflammation (chronic cholecystitis).
- Radioactive tracer detected in other areas. Radioactive tracer found outside of your biliary system might indicate a leak.
Your doctor will discuss the results with you.