A Hepatobiliary Iminodiacetic Acid scan (also known as a HIDA scan or hepatobiliary scintigraphy) is an imaging test that can show how bile moves through a patient’s liver, bile ducts, gallbladder and small intestine. During the procedure, a radioactive tracer is injected into a vein in the arm. The tracer combines with bile in the liver, and as the bile flows through the body, images are captured with a special device called a gamma camera. These images allow specialists to see the structures of the biliary system more clearly, which can help diagnose issues the patient might be experiencing.
The HIDA scan procedure begins by injecting a substance called a radioactive tracer into a vein in the arm. This tracer travels through the bloodstream to the liver, where it is absorbed by the body’s bile-making cells.
Bile is a fluid produced by the liver that aids in the digestion of fats and removing waste from the body. The tracer travels with the bile produced by the liver into the gallbladder — the small organ behind the liver where bile is stored — and then flows on to the small intestine.
As the radioactive tracer moves with the bile through the body during a HIDA scan, your healthcare provider will use a special sort of imaging device called a gamma camera (also known as a nuclear medicine scanner) to take a series of images.
The images created by the gamma camera show the tracer flowing from the liver into the gallbladder and then into the small intestine. The images produced during a HIDA scan should reveal any blockages, bile duct injuries, a biliary leak or other factors that might be causing issues for the patient.
The procedure usually lasts about an hour but could last a few hours depending on how extensive the scanning is. The patient will need to remain still during the hepatobiliary scintigraphy process, so the images are clear and accurate.
In some cases, the patient may receive an IV injection of a medicine called sincalide during the test, which causes the gallbladder to contract and empty.
HIDA scans can be useful in diagnosing a range of gallbladder and bile duct issues, along with other serious conditions than can impact the function of the liver and gallbladder. Conditions that can be diagnosed or evaluated with HIDA scans may include:
Cholecystitis (gallbladder inflammation): cholecystitis often involves sudden, severe pain in the upper belly, often accompanied by fever. It is usually caused by gallstones blocking a bile duct. Patients can experience acute cholecystitis, meaning a one-time issue, or chronic cholecystitis, which involves repeated episodes.
Bile duct obstruction: This condition occurs when there is a blockage in a bile duct, which can prevent the flow of bile from the liver to the gallbladder and small intestine.
Congenital issues with the bile ducts such as biliary atresia, which is a rare condition sometimes present at birth in which an infant’s bile ducts are narrow, blocked or did not form correctly.
Postoperative complications, such as bile duct injury, bile leaks and fistulas.
A HIDA scan is usually performed to diagnose or evaluate conditions involving the gallbladder, biliary ducts and liver. Symptoms or conditions that might be diagnosed or evaluated with a HIDA scan include:
Abdominal pain, especially if it’s on the right side of the abdomen, which may indicate gallbladder inflammation (AKA cholecystitis) or problems with how the gallbladder releases bile. Sudden, severe abdominal pain is the most common reason a hepatobiliary iminodiacetic acid scan is performed.
Evaluation of your gallbladder ejection fraction, which is how much bile the gallbladder releases when it contracts. HIDA scans that reveal very low gallbladder ejection fraction might suggest a patient has cholecystitis, which is chronic or acute inflammation of the gallbladder.
Evaluation of a patient’s liver function following a liver transplant. Patients who have had a liver transplant may need to undergo multiple HIDA scans following the surgery.
Post-operative issues following gallbladder surgery or upper GI tract surgery, including fever or pain
Biliary atresia, a rare and dangerous condition sometimes seen in newborns in which the bile ducts didn’t properly form during fetal development.
Evaluation following the placement of a biliary stent: a bile duct stent is a hollow device that’s surgically placed inside a bile duct. A bile duct is sometimes fitted with a stent to hold it open if it was previously blocked, narrowed or partially blocked.
Your doctor should give you detailed instructions on how to prepare before the test, including directions on diet, certain medications you may be taking, what to wear the day of the test and other issues.
Patients are usually instructed not to eat for at least four hours prior to the test, though they may be allowed to drink clear liquids. Be sure to tell your healthcare provider before the test about any medications you may be taking, including prescription medicines, over-the-counter medications, vitamins and supplements.
Be sure to tell your doctor before the test if you’re pregnant, may be pregnant. Because of potential harm radiation can cause to a developing fetus, nuclear medicine testing usually not performed on those who are pregnant or may be pregnant.
The radioactive tracer substance utilized in HIDA scans can travel through the body and get incorporated into your breast milk. Given that, you’ll need to stop breastfeeding for 72 hours after the test, and discard any milk you pump. Utilize stored breastmilk or formula during this time.
You’ll usually be provided with a hospital gown to wear during the HIDA scan procedure, but it might be helpful to wear loose-fitting clothing that can be easily taken on and off to the appointment. Leave any jewelry or other metal objects at home, as you’ll likely be asked to remove them before the procedure. Patients will be asked to remove most or all of their clothing and change into the hospital gown before the scan begins.
Be sure to follow your doctor’s instructions, but once the procedure is complete, you should be able to leave immediately and resume your regular diet and activities. Hepatobiliary imaging usually doesn’t involve any sort of sedation or anesthesia, so unless you’re in severe pain or need the support, you usually won’t need to bring a person to drive you home after the procedure.
Other than the needle stick involved in the placement of the IV that delivers the radioactive tracer to the bloodstream, a HIDA scan is painless.
That said, you may experience pain during a HIDA scan due to symptoms of the condition your healthcare provider is attempting to diagnose, as some conditions involving the gallbladder and bile ducts can cause moderate to severe pain.
Because of how some pain medication might impact the accuracy of the test, patients might not be able to utilize those medications during a HIDA scan. Patients will need to stop taking morphine, codeine and other opiates at least six hours before the test.
There are very few risks associated with HIDA scanning, and serious complications are rare. Risks you should talk to your doctor about may include:
Allergic reaction to the tracer utilized during the scan at the injection site
Bruising at the site where the radioactive tracer was injected
Exposure to radiation, though it should be noted that the radiation material and dose delivered during a HIDA scan is less than what you’d likely [receive during a standard CT scan.](
Potential claustrophobia issues, as the scanning camera has to be close to the abdomen during the procedure to get clear images of internal structures like the gallbladder and small intestine.
Possible harm to a developing fetus due to radiation exposure, which is why those who are pregnant or may be pregnant should not have most nuclear medicine tests.
Potential contamination of breast milk by the tracer utilized in the test, which is why patients shouldn’t breastfeed for at least 72 hours/3 days after a HIDA scan
The results of a HIDA scan are often very helpful in understanding conditions related to the bile system, and can often be used to confirm a diagnosis or rule out certain conditions as the cause. Results your HIDA scan may show include:
A finding that the radioactive tracer moved freely through the biliary system, which may indicate that issues a patient is experiencing aren’t due to a biliary problem
Inability to see the radioactive tracer in the gallbladder, which might indicate acute gallbladder inflammation (AKA acute cholecystitis)
Slow movement of the radioactive tracer through the biliary system, which might indicate a problem with liver function, an obstruction or blockage
Low gallbladder ejection fraction, which might indicate chronic inflammation (AKA chronic cholecystitis)
Radioactive tracer detected in areas outside biliary system, which might indicate bile leaks