What Is a Hepatobiliary Iminodiacetic Acid (HIDA) Scan?

A hepatobiliary iminodiacetic acid (HIDA) scan is a type of nuclear imaging test. It lets a healthcare provider look at the bile ducts, gallbladder, and liver. It is sometimes also called a cholescintigraphy or hepatobiliary scintigraphy.

During this test, a tracer that contains a small amount of radioactive material is injected into the blood. Images captured during the procedure show how the tracer moves through the body. The test gives healthcare providers a picture of how the gallbladder and liver are working. It may take about an hour to complete. 

This article looks at the HIDA scan, its purpose, and its risks. It will also help you understand what to expect during this test and how to prepare for it.

Purpose of the HIDA Scan

A HIDA scan can be used for a few different purposes, including:

• Diagnosing problems with the gallbladder
• Determining how the liver excretes bile
• Determining the flow of bile as it leaves the liver and enters the small intestine

Along with the HIDA, an X-ray and an abdominal ultrasound might also be done. Some of the conditions that might be diagnosed or evaluated with this test include:

• Biliary atresia or other congenital bile duct conditions 
• Leaks or complications in the biliary system, such as fistulas
• Inflammation of the gallbladder (cholecystitis)
• Blockage of the bile duct
• Post liver transplant assessment

Risks and Contraindications

A HIDA is a nuclear medicine test. This type of test isn't usually done in pregnant people. If there’s a chance you may be pregnant, you should let your practitioner or the radiology staff know before having the test. You should also let your healthcare provider know if you are breastfeeding. This may also affect the decision to have this test.

The risks of the HIDA scan are mostly related to the tracer or other drugs you may be given during the test. These risks are low but can include:

• A bruise, rash, or swelling where the tracer is injected
• A small exposure to radiation
• Rare allergic reactions to the substances used during the test

Preparing for Your Test

You will be given instructions on how to prepare for the test. It’s important to tell your healthcare provider about any current medications or supplements you're taking. This is because they will need to give you instructions on how to take your medications on the day of the test. In some cases, you might be given a drug to take at home before you come in for the test.

Timing

During this test, the tracer moves through the liver, gallbladder, bile duct, and into the small intestine. This typically takes between an hour and an hour and a half. In some cases, though, it may take as long as four hours. Be sure to ask your healthcare provider how much time to allow.

What to Wear

For this test, you will need to remove clothing and change into a hospital gown. Any metal objects will also need to be taken off, including piercings. It may be easier to leave jewelry at home.

Food or Drink

Typically, you will need to stop eating or drinking for about 4-8 hours before the test. In some cases, clear liquids might be allowed, such as:

• Water
• Plain tea or coffee
• Apple juice
• Lemonade
• Lemon/lime soft drinks

If you're not sure, ask your healthcare provider.

What to Bring

Besides your health insurance card, you don't need to bring anything to this test. You may want to consider bringing a book or something to do while you're waiting.

What to Expect During the Test

A HIDA scan is performed by imaging technicians at a hospital or radiology center.

Pre-Test

Before the test, you'll probably be asked to complete some forms. You may also need to answer questions such as what medications you take and if you have had previous surgeries, especially on the abdomen. If you are female, you'll be asked if you might be pregnant and/or the date of your last menstrual period.

Throughout the Test

During the test, you'll be asked to lie on your back on a table. Once you're comfortable, the technician will inject the tracer into one arm. You may feel pressure or a cold sensation. In some cases, other drugs may be injected. This may include:

• Kinevac (sincalide) or cholecystokinin, which activates the gallbladder
• Morphine, which helps guide the tracer to the gallbladder

Morphine is a pain medication that may cause drowsiness.

It’s important to stay still during this test so the images will be clear. The technician will move a gamma camera over your abdomen to follow the tracer as it moves through your body.

Post-Test

The imaging team will tell you if you need to follow any restrictions for the rest of the day. After the test is over, most people will be able to have some food and resume their normal routine. The tracer will pass through the body and be excreted in stool or urine.

What to Expect After the Test

There are usually no special instructions to follow after the test is over. If there is something unique about your situation, though, the healthcare team will let you know.

You should not have any side effects after the test. The radioactivity of the tracer only lasts for a few hours. It's no longer radioactive by the time the test is over. Drinking plenty of water will help the tracer pass out of your body more quickly.

If you received morphine, you should not drive yourself home. Plan to have someone pick you up or call a rideshare or cab.

Interpreting the Results

A healthcare provider will explain the results of the test. They will also let you know if you need to take any next steps. It’s important to discuss your results with a healthcare provider so they can be put in the proper perspective. The test could show one of several results:

• The tracer moved through the gallbladder and small intestine normally, or as expected.
• The tracer moved slower than expected. This could be because of an obstruction or blockage in a bile duct or an irregularity in liver function. 
• The tracer did not enter the gallbladder. This may mean you have acute cholecystitis, or an inflamed gallbladder.
• The tracer left the gallbladder in amounts lower than what is expected. This could mean the gallbladder is chronically inflamed, a condition called chronic cholecystitis.
• The tracer is found outside the biliary system. This could mean there’s a leak in the bile duct system or a perforation in the gallbladder.

Summary

A HIDA scan helps healthcare providers understand how well your bile ducts, gallbladder, and liver are functioning. During this test, a technician passes a camera over your body to follow an injected radioactive tracer.

The test can usually be completed in an hour or two. You should be able to go home afterward. Your healthcare provider will discuss the results with you when they are available. 

A Word from Verywell

A HIDA scan is non-invasive, though you may need to block out part of a day to get it done. This nuclear imaging test gives your healthcare provider information about your biliary system, in particular the gallbladder.

A HIDA scan may help explain symptoms you've been having. It’s important to discuss the results thoroughly with a medical professional. This will help you understand what future treatment or management will be needed.