A HIDA scan is a nuclear medicine imaging test used to check how bile moves through the liver, gallbladder, bile ducts and small intestine. It can help healthcare providers evaluate gallbladder function, bile duct blockage, bile leaks and certain liver or biliary tract problems.
HIDA stands for hepatobiliary iminodiacetic acid. The test is also called a hepatobiliary scan, cholescintigraphy or hepatobiliary scintigraphy. During the scan, a small amount of radioactive tracer is injected into a vein, and a special camera tracks how the tracer moves through the biliary system.
What is a HIDA scan?
A HIDA scan is an imaging test that shows how well your liver, gallbladder and bile ducts are working. Unlike some imaging tests that mainly show what organs look like, a HIDA scan can show how bile flows through the biliary system.
Bile is a digestive fluid made by the liver. It travels through bile ducts and is stored in the gallbladder before being released into the small intestine. If bile does not move normally, it may suggest inflammation, blockage, poor gallbladder emptying or another problem.
A HIDA scan is usually performed in a hospital or imaging center by a nuclear medicine team.
Why is a HIDA scan done?
A healthcare provider may order a HIDA scan when symptoms, blood tests, ultrasound or other imaging results suggest a possible problem with the gallbladder or bile ducts.
A HIDA scan may help evaluate:
- Acute cholecystitis, which is inflammation of the gallbladder.
- Chronic gallbladder disease or poor gallbladder function.
- Bile duct blockage or abnormal bile flow.
- Bile leaks, sometimes after surgery or injury.
- Biliary atresia in infants.
- Possible complications after gallbladder, liver or bile duct surgery.
The test is often used along with other information, such as symptoms, physical examination, blood tests, ultrasound, CT scan or MRI. A HIDA scan result is not usually interpreted in isolation.
What symptoms may lead to a HIDA scan?
A HIDA scan may be considered when a person has symptoms that could involve the gallbladder or biliary system. These may include:
- Pain in the upper right abdomen.
- Pain after eating fatty meals.
- Nausea or vomiting.
- Fever with abdominal pain.
- Jaundice, or yellowing of the skin or eyes.
- Abnormal liver or bile duct blood tests.
- Ongoing symptoms despite a normal or unclear ultrasound.
These symptoms can have many causes, so a healthcare professional decides whether a HIDA scan is the right test.
How does a HIDA scan work?
During a HIDA scan, a radioactive tracer is injected into a vein, usually in the arm. The tracer travels through the bloodstream to the liver. Liver cells take up the tracer and release it into bile. From there, the tracer should move through the bile ducts into the gallbladder and small intestine.
A gamma camera takes images over time. The healthcare team watches the movement of the tracer. If the tracer does not appear where expected, moves slowly or does not enter the gallbladder, it may suggest a problem with bile flow or gallbladder function.
How to prepare for a HIDA scan
Preparation instructions can vary by clinic, hospital and medical situation. Always follow the instructions given by your healthcare team.
Common preparation steps may include:
- Fasting for several hours before the test.
- Reviewing your medicines with your healthcare provider.
- Telling the team if you are pregnant, may be pregnant or breastfeeding.
- Arriving with enough time because the scan may take longer depending on results.
- Bringing previous imaging results if your healthcare team requests them.
Some medicines can affect gallbladder function or test interpretation. Do not stop a prescribed medicine unless your healthcare provider tells you to do so.
What happens during the test?
The exact steps may vary, but a typical HIDA scan may involve the following:
- You lie on an imaging table.
- An IV line is placed in a vein.
- A radioactive tracer is injected through the IV.
- A special camera takes images as the tracer moves through your liver and bile ducts.
- You may need to stay still while images are taken.
- In some cases, additional medicine or a fatty meal may be used to stimulate the gallbladder.
- More images may be taken to see how the gallbladder fills or empties.
The test is usually not painful, although you may feel a brief pinch when the IV is placed. Some people feel uncomfortable from lying still for a long time.
How long does a HIDA scan take?
A HIDA scan may take about one to several hours, depending on why the test is being done and how quickly the tracer moves through the biliary system.
Some scans are completed relatively quickly. Others take longer if delayed images are needed, if the gallbladder does not fill as expected or if the healthcare team needs additional information about gallbladder emptying.
Ask the imaging center how long you should plan to be there, especially if you need transportation, childcare or time off work.
What is a gallbladder ejection fraction?
Some HIDA scans include a measurement called the gallbladder ejection fraction. This estimates how well the gallbladder empties after stimulation.
To measure this, the healthcare team may use a medicine that makes the gallbladder contract or may use a fatty meal depending on the protocol. The scan then measures how much tracer leaves the gallbladder.
A low ejection fraction may suggest poor gallbladder emptying, but the result must be interpreted with symptoms and other test findings. A number alone does not always explain a patient’s pain.
What can HIDA scan results show?
Results depend on the pattern of tracer movement. Your healthcare provider or radiologist will interpret the scan in the context of your symptoms and medical history.
| Possible finding | What it may suggest |
|---|---|
| Tracer moves normally through the liver, gallbladder and intestine | Bile flow appears normal during the scan. |
| Gallbladder does not show up | May suggest acute gallbladder inflammation or blockage of the cystic duct. |
| Tracer moves slowly | May suggest bile flow problems, liver function issues or partial obstruction. |
| Tracer appears outside the expected bile ducts or intestine | May suggest a bile leak. |
| Low gallbladder ejection fraction | May suggest poor gallbladder emptying in the right clinical context. |
Your healthcare provider should explain what your result means and whether you need more tests, treatment or follow-up.
Is a HIDA scan safe?
A HIDA scan uses a small amount of radioactive tracer. For most people, the radiation exposure is considered low, but the test is still ordered only when the expected benefit is greater than the risk.
Possible risks or side effects may include:
- Brief discomfort or bruising at the IV site.
- Rare allergic reaction to a medicine or tracer.
- Radiation exposure from the nuclear medicine tracer.
- Possible side effects from medicines used during the test, depending on the protocol.
Tell your healthcare team if you are pregnant, may be pregnant or breastfeeding. Special precautions or a different test may be needed.
Can you eat before a HIDA scan?
Many patients are told not to eat for several hours before a HIDA scan. Fasting helps the gallbladder fill properly so the test can be interpreted more accurately.
However, fasting too long may also affect the test in some situations. Follow the exact instructions from your imaging center rather than guessing.
Can you take medications before a HIDA scan?
Some medicines can affect the gallbladder, bile flow or test results. Your healthcare team may ask you to avoid certain medicines before the scan, depending on your situation.
Do not stop prescription medicine on your own. Ask the ordering provider or imaging center which medicines to take and which to hold before the test.
What happens after a HIDA scan?
Most people can return to normal activities after the scan unless they were given medicine that causes drowsiness or unless their healthcare team gives different instructions.
The tracer leaves the body over time, mainly through urine and stool. Drinking fluids may be recommended unless you have been told to restrict fluids.
A radiologist or nuclear medicine physician reviews the images and sends a report to the ordering healthcare provider. Your provider will explain the result and next steps.
HIDA scan vs ultrasound
Ultrasound is often one of the first imaging tests used for gallbladder symptoms because it can show gallstones, gallbladder wall thickening and bile duct dilation. A HIDA scan is different because it evaluates bile movement and gallbladder function.
In some cases, an ultrasound may look normal or unclear, but symptoms continue. A healthcare provider may then order a HIDA scan to gather more functional information.
Questions to ask before the test
Before a HIDA scan, useful questions may include:
- Why am I having this test?
- How long should I fast before the scan?
- Should I take my usual medicines?
- Will my gallbladder ejection fraction be measured?
- How long should I expect to be at the imaging center?
- Are there any special precautions if I am pregnant or breastfeeding?
- When and how will I receive the results?
When to seek urgent medical care
A HIDA scan is a diagnostic test, not emergency treatment. Seek urgent medical care if you have symptoms such as:
- Severe or worsening abdominal pain.
- Fever with right upper abdominal pain.
- Yellowing of the skin or eyes.
- Confusion, fainting or severe weakness.
- Persistent vomiting.
- Chest pain or trouble breathing.
Use local emergency services if symptoms are sudden, severe or life-threatening.
Quick summary
- A HIDA scan checks bile flow through the liver, gallbladder and bile ducts.
- It uses a small amount of radioactive tracer injected through an IV.
- It may help diagnose gallbladder inflammation, bile duct blockage, bile leaks or poor gallbladder function.
- You may need to fast before the test.
- The scan may take one to several hours depending on the situation.
- Results should be interpreted with symptoms, blood tests and other imaging.
Frequently asked questions
Is a HIDA scan painful?
A HIDA scan is usually not painful. You may feel a brief pinch from the IV, and some people feel uncomfortable from lying still during the imaging process.
How long does a HIDA scan take?
The test may take about one to several hours. The exact time depends on why the scan is being done, how quickly the tracer moves and whether delayed images or gallbladder ejection fraction measurement are needed.
What does it mean if the gallbladder does not show up on a HIDA scan?
If the gallbladder does not fill with tracer, it may suggest cystic duct blockage or acute gallbladder inflammation. Your healthcare provider will interpret this with your symptoms, blood tests and other imaging.
What is a normal HIDA scan?
A normal HIDA scan generally shows tracer moving from the liver into the bile ducts, gallbladder and small intestine as expected. If an ejection fraction is measured, your provider will explain whether the result is within the expected range for that lab or protocol.
Can a HIDA scan show gallstones?
A HIDA scan is not mainly used to show gallstones directly. Ultrasound is often better for seeing gallstones. A HIDA scan is more useful for evaluating bile flow and gallbladder function.
Is radiation from a HIDA scan dangerous?
A HIDA scan uses a small amount of radiation. For most people, the risk is considered low, but the test should only be done when medically appropriate. Tell your healthcare team if you are pregnant, may be pregnant or breastfeeding.
Can I drive after a HIDA scan?
Many people can return to normal activities after a HIDA scan. However, if you receive medicine that causes drowsiness or your healthcare team gives special instructions, you may need someone to drive you home.