Hepatobiliary iminodiacetic acid scan or HIDA scan is an imaging test that captures the images of the organs of the body to diagnose the presence of various medical ailments related to those organs. It is also called the cholescintigraphy and hepatobiliary scintigraphy. This test finds its use for gallbladder ejection fraction. Gallbladder ejection fraction is a test that measures the rate of release of bile from the gall bladder. Doctors usually use this test with ultrasound tests and X-rays.
For the procedure, your doctor will inject a radioactive tracer into the vein of your arm. It will travel through your blood into the liver to travel with the bile to your gall bladder. The tracer will finally pass through your bile ducts into the small intestine. A gamma camera (nuclear medicine scanner) will monitor the flow of the tracer while it travels from the liver to the small intestine to create computer images.
Why do you need HIDA scan?
Your doctor will recommend the HIDA scan to evaluate the condition of your gall bladder. It also helps to view the bile-excreting function of the liver and monitor the flow of bile from the liver to the small intestine. The test held to diagnose various medical conditions and ailments like:
- Cholecystitis (inflammation of your gall bladder)
- To assess liver transplant
- Bile duct obstruction or blockages
- Congenital abnormalities like biliary atresia occurring in the bile duct (biliary atresia is a condition affecting the infants)
- Post-operative complications including fistulas and bile leaks.
Preparing for the HIDA scan
You need to prepare before you go for the HIDA scan. Your doctor will ask you to avoid eating anything four hours before the test. However, you can drink clear liquids. Give the details of all the medications and supplements that you are consuming to the doctor. You may require to remove all the accessories and jewelry that you will be wearing, prior to the procedure.
Your doctor will ask you to stop taking certain medications before the procedure as these medications don’t allow the scan to work well. Some medications that you take regularly may affect the scan. So, you will have to stop them temporarily. However, your doctor will allow you to continue taking the medications after the test. He or she may prescribe a medication for the effective functioning of the scan and to get better images. You will have to start the medication a few days prior to the HIDA scan or immediately before the test.
What to expect?
Before the test
During the test
During the HIDA scan, the doctor will inject an intravenous injection of a drug called Kinevac that will contract your gall bladder and make it empty. In some cases, the patients receive another drug called Morphine that makes it easier for the team to view the gall bladder. Next, the team will position a gamma camera over your abdomen to capture the images of the tracer while it travels throughout your body. You will have to stay still as the procedure lasts for about an hour. You may take deep breaths to reduce the discomfort.
The radiologist will track the tracer throughout your body on a computer. The tracer moves through the blood in your body to the liver where bile-producing cells will absorb the tracer. The tracer will combine with these cells to travel into your gall bladder & bile duct to reach the small intestine. However, you may need to undergo additional imaging within a day or two, if the captures images are not helpful in diagnosis.
After the test
In most of the cases, the doctor allows leaving on the same day as that of the scan. The radioactive tracer is present in a small amount and it loses its reactivity by the next day or passes through the stools and urine. You may drink adequate water to allow it to pass out of your body soon.
HIDA scan with CCK
Your doctor or team may recommend a HIDA scan with cholecystokinin (CCK). Cholecystokinin is a hormone that is responsible for the emptying of your gall bladder and the release of the bile. If there’s a need for this scan, the team will give you the medication through the veins or by mouth. Your team will capture the images of your gall bladder before giving you CCK and after the scan with CCK.
Results of the scan
If the results of the HIDA scan are normal then your gall bladder is functioning well and maintains its size & shape. Normal results of the scan reveal healthy liver and small intestine. Abnormal results may reveal the presence of:
- Gall stones
- Gall bladder problems
- Abnormal growth
- Blockage in your bile duct
The distinct types of results that very after the HIDA scan may include:
- Slowly moving radioactive tracer- This indicates the presence of an obstruction or a blockage, or even problems with the functioning of your liver.
- Tracer not visible- If the radioactive tracer is not visible in your body, there might be acute inflammation present in your body.
- Low gall bladder ejection fraction- If the amount of radioactive tracer that leaves your body is low, chronic inflammation or chronic cholecystitis may be present in your body.
- Tracer detected in other organs- If the tracer is found outside your biliary tract, there may be chances of biliary leaks.
Risks of HIDA Scan
There are a few risks associated with HIDA scan that may be:
- Bruising at the site of injection
- Allergic reaction to the medications used for the HIDA scan as they may contain radioactive tracers.
- Radiation exposure
Ensure that you inform your doctor if you are pregnant or a breastfeeding mother. There are chances of harm to the baby. Hence, doctors usually don’t recommend nuclear medicine tests like the HIDA scan to pregnant women or breastfeeding mothers.