A HIDA scan, also called cholescintigraphy or hepatobiliary scintigraphy, is an imaging test used to view the liver, gallbladder, bile ducts, and small intestine.
The scan involves injecting a radioactive tracer into a person’s vein. The tracer travels through the bloodstream into the body parts listed above. A special camera takes pictures to track the tracer’s movement and transmit images onto a computer screen for observation and diagnosis.
This article discusses HIDA scanning and outlines what a person can expect before, during, and after the procedure.
A HIDA scan may be done to:
- measure the rate at which the gallbladder releases bile, commonly referred to as gallbladder ejection fraction
- check the liver’s bile-excreting function
- follow the path of bile from the liver to the small intestine
- assess the outcome of a liver transplant
- find the cause of pain originating in the right side of the abdomen
- uncover the cause of jaundice or a yellowish hue to the skin
HIDA scans can help diagnose the following:
- biliary atresia, a rare congenital or inherited bile duct abnormality
- cholecystitis or inflammation of the gallbladder
- complications of operations, such as bile leaks or fistulas, which are abnormal connections between two organs
- obstruction of the bile duct
Doctors may use X-rays and ultrasounds in conjunction with HIDA scans to confirm a diagnosis.
After a person has fasted for 4 to 12 hours, they may be allowed clear fluids, but always check this with a doctor. Before undergoing the procedure, all individuals should tell their doctor about any medications and supplements they are taking.
For example, those who have had an X-ray using barium contrast material or who have taken a medication containing bismuth, such as Pepto-Bismol, in the days before the HIDA scan should let their doctor know. Both barium and bismuth can impact the outcome of the test.
Pregnant women will not usually be given a HIDA scan as there may be a potential risk to the fetus. Breast-feeding women will be advised to avoid feeding their infant for several days following the scan to ensure the radioactive tracer has left their system.
Upon arrival at the hospital or clinic, a person will be asked to remove any jewelry and metal accessories. They may also be required to change into a hospital gown.
During the procedure:
- The person will lie down on a table and be instructed to remain still throughout the scan.
- A specialist will insert an intravenous (IV) line into the person’s arm or hand and inject a radioactive tracer. The person may experience a slightly cold sensation or feeling of pressure while this is happening.
- A technician will position a gamma camera above the person’s stomach to capture images.
- The tracer will move through the IV line into the bloodstream. From there, it will travel to the liver. At this stage, bile-making cells in the liver absorb the tracer and carry it through the gallbladder, bile duct, and small intestine. This process may take approximately 60 to 90 minutes, although it can take up to 4 hours in some cases.
- A technician will control the camera, and a radiologist will view the images on a screen.
If anyone experiences discomfort at any stage of the procedure, it is essential to tell the medical staff. Deep breathing may help alleviate discomfort.
Some people may be given more medications before, or during, the scan. For example, if the doctor orders a HIDA scan with cholecystokinin (CCK), which is a hormone that causes the gallbladder to release bile, the person will be given the medication sincalide (injection) or Kinevac (orally). Some people may be given morphine to aid the tracer’s movement into the gallbladder.
If the images from the scan are not clear, some people may need to undergo a second scan within 24 hours.
Following a HIDA scan, most people will be able to go about their day as normal.
A person should drink plenty of water to help speed up the radioactive tracer’s movement out of the body through urination and bowel movements.
HIDA scan results can be classed as:
- Normal: This means the tracer moved freely from the liver into the gallbladder and small intestine.
- Slow movement: If the tracer moved slowly through the body, this might suggest an obstruction or blockage in the gallbladder or bile duct, or it indicates below optimal liver function.
- Not present: If there is no sign of the radioactive tracer in the gallbladder, it can be a sign of acute inflammation of the gallbladder or acute cholecystitis.
- Low gallbladder ejection fraction: If a person takes CCK to empty the gallbladder, yet the amount of the radioactive tracer leaving the gallbladder is abnormally low, it can indicate chronic inflammation of the gallbladder or chronic cholecystitis.
- Radioactive tracer detected in other parts of the body: In cases where the tracer makes its way to other areas of the body, it suggests a leak in the biliary system.
A doctor will use these results — plus the results of other tests, as well as a person’s signs and symptoms — to help inform their diagnosis.
There are relatively few risks associated with a HIDA scan. Potential risks include:
- Allergic reactions: Some people may react to the medications used during the scan.
- Bruising: Some bruising may occur at the site of the injection or IV line.
- Exposure to radiation: People undergoing HIDA scans are exposed to radiation, even though the amounts are minimal.
HIDA scans vary in price. In some cases, insurance may cover the cost. Healthcare Bluebook quotes $1,120 as the fair price for a HIDA scan.
A HIDA scan is a useful test to help diagnose conditions in the liver, gallbladder, bile ducts, and small intestine. It involves tracking a radioactive tracer’s movement as it moves through the body’s bile system.
There is little preparation necessary before undergoing a HIDA scan, although it is important that women who are breast-feeding or pregnant inform their doctor before the procedure begins. Side effects are rare, with the benefits of undergoing a HIDA scan usually outweighing the potential risks.