The HIDA scan, also known as a hepatobiliary iminodiacetic acid scan, is a diagnostic imaging procedure commonly used to detect liver,gallbladder, and bile duct problems.
For a HIDA scan, a radioactive tracer is injected into a vein in the arm, also known as cholescintigraphy or hepatobiliary scintigraphy. The tracer goes through the bloodstream to the liver, which is taken up by bile-producing cells. The tracer is then carried by the bile into the gallbladder and through the bile ducts to the small intestine.
A nuclear medicine scanner (gamma camera) makes computer images by tracking the tracer's movement from the liver into the gallbladder and small intestine.
Why is the HIDA scan done?
A HIDA scan is usually performed to assess the gallbladder. It's also used to examine the liver's bile-excreting activity and to trace the movement of bile from the liver into the small intestine. A HIDA scan is frequently used in conjunction with X-rays and ultrasounds.
A HIDA scan may help to determine the presence of a number of disorders and conditions, including:
- Bile duct obstruction
- Gallbladder inflammation (cholecystitis)
- Congenital abnormalities in the bile ducts
- Assessment of liver transplant
- Postoperative complications, such as fistulas and bile leaks
A HIDA scan may be performed as part of a test to determine the rate at which bile is released from the gallbladder (gallbladder ejection fraction).
What are the risks involved in the HIDA scan?
A HIDA scan poses only a few risks. These include:
- Bruising at the injection site
- Allergic reaction to drugs carrying radioactive tracers used in the scan
- Radiation exposure
Inform the physician if you think you might be pregnant or breastfeeding. Nuclear medicine diagnostics, such as the HIDA scan, are rarely conducted in pregnant women due to the risk of injury to the baby.
How should I prepare for a HIDA scan?
The healthcare team will provide specific instructions on preparing for a HIDA scan. Make a point of implementing them. Here are some general tips for preparing for a HIDA scan:
- If you are pregnant, suspect you are pregnant or are breastfeeding, you must notify the healthcare provider before having a HIDA scan.
- Inform the physician about your medications, including vitamins and herbal supplements. Some medications may be advised to be discontinued before your scan by the provider because they could interfere with the accuracy of the results.
- Jewellery and other accessories should be left at home or removed before the scan. These items could make the procedure difficult.
- Before the exam, let the doctor know if you fear enclosed or cramped situations because the scanning equipment needs to be placed near the body to provide the best images. The camera has two open sides and is not a closed tube. It’s usually positioned over the stomach and doesn’t cover the face.
- Before the HIDA scan, individuals must fast (not eat or drink anything but water) for at least four hours. If you need to fast for a longer period of time, the provider will inform you.
- Newborn babies may need to be prepped for three to five days before the scan, and you will be given instructions by the pediatric staff.
The doctor will evaluate the signs and symptoms, as well as the results of other tests, to determine a diagnosis.
A HIDA scan provides the following results:
The radioactive tracer moved freely from the liver into the gallbladder and small intestine with the bile.
Slow movement of radiotracer
This could suggest an obstruction or blockage or the liver is not functioning properly.
Absence of radiotracer in the gallbladder
This could indicate acute cholecystitis caused by a blockage.
Unusually low gallbladder ejection fraction
The gallbladder ejection fraction is determined by the amount of bile the gallbladder can release when stimulated with medication. A normal ejection fraction is typically above 30% to 35%. A low ejection fraction could be a sign of chronic cholecystitis.
Radiotracer detected outside of expected areas
This might indicate a biliary (bile duct) leak.
It's important to remember that the provider will explain the results to you, no matter what they are. Feel free to ask them any questions you have!