If you’re experiencing certain issues with your digestive system, your doctor may want to order specific tests to get a better look. Hepatobiliary scintigraphy, otherwise known as a HIDA scan or cholescintigraphy, can give your healthcare provider an inside look at the accessory organs that make up your digestive system (gallbladder, liver, and also the small intestine). A HIDA scan is relatively non-invasive and can help your doctor diagnose specific issues, usually related to the gallbladder or bile ducts. Read on to learn more about what a HIDA scan is, how to prepare, and what risks are involved with the test.
What Is a HIDA Scan?
A HIDA scan is a specific type of nuclear medicine diagnostic imaging test. Before the scan, a radioactive tracer is injected into the patient’s vein. During the scan, a camera is used to take pictures of the digestive system organs and the bile ducts. A HIDA scan may also be performed in conjunction with another diagnostic test, known as a gallbladder ejection fraction test. This is a test that measures how quickly or slowly bile is released from the gallbladder and essentially tests how well the gallbladder is performing. HIDA scans may also be used together with a battery of other diagnostic tests, such as ultrasound or X-ray.
What Can Be Diagnosed with a HIDA Scan?
A HIDA scan is comprehensive enough to diagnose many different diseases and conditions. If you’re experiencing abdominal pain, are experiencing jaundice or other liver-related issues, or have had a liver transplant, this test is commonly ordered to assess the gallbladder and surrounding organs. Some of the conditions that are diagnosed with a HIDA scan include:
- Inflammation of the gallbladder (cholecystitis)
- Bile duct obstruction
- Biliary atresia (an abnormality of the bile ducts)
- Post-operative complications, such as fistulas or bile leaks
A HIDA scan is also used to assess certain things, such as:
- Liver function after a liver transplant
- Finding the cause of jaundice (yellowing of the skin and eyes)
- Looking at the liver and small intestine for possible problems
- Checking the bile-secretion function of the liver
- Measuring the rate of bile released from the liver (this is the gallbladder ejection fraction procedure)
Your physician may have other reasons for evaluating your gallbladder and liver, but the test is often ordered based on symptoms reported by the patient, or to assess after a liver transplant. HIDA scans are common diagnostics for post-operative patients following a liver transplant.
How to Prepare for the Test
There is some preparation involved with the HIDA scan. Your healthcare provider will ask you to completely fast from 4 to 12 hours, depending on their direction. After the fasting period, you may be allowed clear fluids, but always check with your physician first. Also, let your physician know about all medications you are taking, including over-the-counter and supplement medications. It is also important to let them know if you have had any other diagnostic tests in the days or weeks leading up to the HIDA scan. A barium X-ray or a medication containing bismuth (such as Pepto-Bismol) can affect the results of the test.
If you are pregnant or breastfeeding, let your physician know. Pregnant women are advised not to have HIDA scans because of the risk to the fetus. Breastfeeding women may have a HIDA scan if necessary, but cannot breastfeed for several days afterward until the radioactive tracer has left their system.
Because of the nature of the test, do not wear jewelry or metal accessories on the day of the test, as you’ll likely be asked to remove them.
What to Expect from a HIDA Scan
The HIDA scan is relatively non-invasive. During the procedure, the patient will lie down on an imaging table, and an intravenous (IV) line will be inserted into the arm or hand. Then, the physician or technician will inject the radioactive tracer into the line. The patient may feel a sensation of cold or pressure immediately following the injection.
Directly above the patient’s stomach, a technician will place a gamma camera to track the tracer. It will take a few moments for the tracer to travel through the bloodstream to the liver. From here, the bile-making cells in the liver will then absorb and carry the tracer to all of the accessory organs (gallbladder, bile ducts, and small intestines). This can be a slow process, and the tracer may need 60 to 90 minutes to complete its journey. In some cases, the procedure can take up to four hours.
A radiologist and technician are usually in the room with the patient. It is the technician's job to move the camera during the procedure, while the radiologist will note and evaluate the results on the screen the camera is projecting to.
Depending on the reasons why a HIDA scan is ordered, a patient may be administered other medications prior to the test. The doctor may have ordered a HIDA with cholecystokinin (CCK). CCK is a hormone that prompts the gallbladder to release bile. In order to aid the process, a patient may be given a sincalide injection or Kinevac, which is taken by mouth. Morphine is also an option to help the radioactive tracer move more quickly through the body.
Risks and Side Effects
HIDA scans are typically safe procedures, but there are some slight risks and side effects to be aware of that your physician will likely review with you prior to the procedure. The most common side effect is an allergic reaction to the radioactive tracer or other medications used with the scan. Patients may also experience bruising at the IV site. It is also important to note that a HIDA scan does expose a patient to a small amount of radiation. The amount is small enough to be safe, but patients should understand exposure.
Understanding HIDA Scan Results
There are several outcomes from a HIDA scan, which your doctor will go over with you after the procedure. Outcomes from a HIDA scan include:
- Normal. There were no problems with the test, the tracer was able to move freely, and liver and gallbladder function are normal.
- Not present. The tracer was not discoverable in the gallbladder. The outcome of these results typically means the patient has inflammation of the gallbladder (also referred to as cholecystitis or acute cholecystitis).
- Low gallbladder ejection fraction. If this was a HIDA scan with CCK, and there are only trace amounts of tracer leaving the gallbladder, this may also indicate gallbladder inflammation or cholecystitis.
- Slow movement. If the tracer moved slowly through the organs, this might indicate a bile duct obstruction or an obstruction in the gallbladder, although it can also be indicative of low liver function.
- Radioactive tracer detected in other parts of the body. If the tracer moved beyond the digestive system organs to other parts of the body, this could indicate a biliary system leak (leak in the bile ducts or hepatobiliary system overall (gallbladder, bile ducts, liver).
Following your HIDA scan results, your physician will follow up with you if more diagnostic tests are needed or with a treatment plan. If you need more information on HIDA scans or are experiencing abdominal pain or digestive system problems, request an appointment with Dr. Sameer Islam. Our office offers the full spectrum of gastrointestinal services, with unique and individualized care for every patient.