What is a HIDA scan?
A HIDA, or hepatobiliary, scan is a diagnostic test. It’s used to capture images of the liver, gallbladder, bile ducts, and small intestine to help diagnose medical conditions related to those organs. Bile is a substance that helps digest fat.
This procedure is also known as cholescintigraphy and hepatobiliary scintigraphy. It might also be used as part of a gallbladder ejection fraction, a test used to measure the rate that bile is released from your gallbladder. It’s also often used along with X-rays and ultrasound tests.
HIDA scans can be used to help diagnose a variety of diseases. These include:
- gallbladder inflammation, or cholecystitis
- bile duct blockages
- congenital bile duct abnormalities, such as biliary atresia, a rare condition that affects infants
- complications following operations, including bile leaks and fistulas, or abnormal connections between different organs
HIDA scans may also be used to evaluate a liver transplant. The scans may be done periodically to make sure the new liver is working properly.
A HIDA scan involves some special preparation:
- Fast for four hours prior to your HIDA scan. Your doctor may allow you to drink clear liquids.
- Inform your doctor about all medications and supplements you are taking.
- Let your doctor know if you are pregnant or breastfeeding.
Once you arrive at your local hospital or medical imaging center, an imaging technician will ask you to:
- change into a hospital gown
- remove all jewelry and other metal accessories home before the procedure
Here’s what to expect at your HIDA scan:
- An imaging technician will instruct you to lie back on a table and stay very still. They will position a camera called a scanner above your belly.
- The technician will put an IV (intravenous) needle into a vein in your arm or hand.
- The technician will inject a radioactive tracer into the IV so it enters your vein.
- The tracer will move through your body’s bloodstream to your liver, where bile-making cells absorb it. Then the tracer will move with the bile into your gallbladder, through the bile duct, and into the small intestine.
- The technician will control the camera so it takes images of the tracer as it moves through your body.
- The technician may also inject a type of pain medicine called morphine through your IV line. This can help move the tracer into your gallbladder.
Your doctor may order a HIDA scan with CCK (cholecystokinin), a hormone that causes your gallbladder to empty and release bile. If this is the case, the imaging technician will give you this medication by mouth or through a vein. They will take images of your gallbladder before and after giving you CCK.
A HIDA scan typically takes between one hour and one-and-a-half hours to complete. But it could take as little as a half hour and as much as four hours, depending on your body functions.
HIDA scans are generally safe. But there are a few risks to be aware of. Potential side effects include:
- an allergic reaction to the medications that contain radioactive tracers used for the scan
- bruising at the site of the IV
- exposure to a small amount of radiation
Make sure to alert your doctor if there’s a chance you could be pregnant or if you’re breastfeeding. Doctors will usually not perform tests involving radiation exposure on pregnant women because it could harm your unborn baby.
Your doctor will work to come to a diagnosis by considering your physical condition, any abnormal symptoms, and your HIDA scan results.
HIDA scan results may be:
|Results||What the scan shows|
|Normal||The radioactive tracer moved freely with your body’s bile from the liver into your gallbladder and small intestine.|
|Slow||The tracer moved slower than normal through your body. This may be a sign of a blockage or a problem with your liver.|
|Not present||If there are no signs of radioactive tracer in your gallbladder on the images, this may be a sign of acute gallbladder inflammation, or acute cholecystitis.|
|Low gallbladder ejection fraction||If the amount of tracer leaving the gallbladder is low after you’ve been given CCK to make it empty, you may have chronic inflammation of the gallbladder, or chronic cholecystitis.|
|Radioactive tracer in other parts of the body||If images show signs of radioactive tracer outside of your liver, gallbladder, bile ducts, and small intestine, you may have a leak in your body’s biliary (bile) system.|
Most people can go normally about their day after having a HIDA scan. Small amounts of the radioactive tracer that was injected into your bloodstream will exit your body in your urine and stool over the course of a few days. Drinking a lot of water can help move the tracer out of your system more quickly.