How does a HIDA scan work?
A HIDA scan (hepatobiliary iminodiacetic acid scan) uses small amounts of radioactive substances called radiopharmaceuticals or radiotracers that a healthcare provider typically injects into your bloodstream.
The radiotracer then travels through your liver and into your gallbladder and your small intestines. The radiotracer gives off energy in the form of gamma rays. Special cameras detect this energy and, with the help of a computer, create detailed pictures that show how your organs and tissues to evaluate their function.
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How do I prepare for a HIDA scan?
Your healthcare team will give you specific instructions to prepare for a HIDA scan. Be sure to follow them. Here are some general guidelines to prepare for a HIDA scan:
- If you’re pregnant, think you might be pregnant or are breastfeeding (chestfeeding), it’s important to tell your healthcare provider before undergoing a HIDA scan.
- Tell your healthcare team about any medications you’re taking, including vitamins and herbal supplements. Your provider may tell you to stop taking certain medications before your scan because they may interfere with the accuracy of the results.
- You should leave jewelry and accessories at home or remove them before the scan. These objects may interfere with the procedure.
- Tell your provider if you have a fear of closed or tight spaces before your exam begins since the scanning equipment needs to be positioned close to your body to get the best pictures. The camera is not a closed tube and is open on two sides. It’s usually positioned over your stomach and doesn’t cover your face.
- You’ll need to fast (not eat or drink anything except for water) for at least four hours before your HIDA scan. Your provider will let you know if you need to fast for longer.
- Newborn babies may need to be pretreated for three to five days prior to the scan, and the pediatric staff will give you instructions.
Do they put you to sleep for a HIDA scan?
HIDA scans don’t typically require anesthesia to put you to sleep (or to prevent pain). In fact, for some scans, you may need to move into different positions.
If you may have issues remaining still during the scan or if your newborn or child is getting the scan, you or your child may be given medicine (a sedative) that makes you relaxed and sleepy — but still awake —during the scan.
How long does a HIDA scan take?
A HIDA scan usually takes one to four hours. In some cases, you may need to return for additional imaging up to 24 hours after the first scan.
What should I expect during a HIDA scan?
A HIDA scan procedure can have slightly different steps depending on which part of your biliary system your healthcare provider is evaluating.
In general, you can expect the following during a HIDA scan:
- You’ll remove any clothing covering your belly, and you’ll have a medical gown to wear.
- You’ll lie on your back on an exam table.
- A nurse or technologist will likely insert an intravenous (IV) catheter into a vein in your hand or arm for the injection of the radiotracer.
- The technologist will place the scanning camera close over your belly.
- When imaging begins, the scanning camera will take a series of images. The camera may rotate around you or stay in one position. While the camera is taking pictures, it’s important to remain very still. This helps ensure the best quality of images.
- You may need to change positions in between images. Your technologist will let you know.
- After the technologist takes an initial series of images, they may give you a medication that causes your gallbladder to empty. This may cause cramping in your upper belly. As your gallbladder empties, they’ll take more images.
- Once the technologist has taken the necessary images, which may take up to four hours, the scan will be finished.
How painful is a HIDA scan?
The HIDA scan itself is painless. If you receive the radiotracer through an IV, you may feel a brief sting or pinch as your provider places the IV in your arm.
However, you may be in pain while undergoing a HIDA scan because of the condition your provider is trying to diagnose. For example, cholecystitis and sphincter of Oddi dysfunction often cause severe pain. And you may not be able to be on pain medication for the scan because some medications alter the function of your biliary system and would interfere with the accuracy of the test.
Opiates (like morphine and codeine), for example, need to be withheld for at least six hours before a HIDA scan.
What should I expect after a HIDA scan?
Depending on the reason for your HIDA scan, you may be able to go home or you’ll return to your hospital room.
Be sure to drink lots of fluids for the next 24 hours after your scan to help flush the radiotracer out of your body. Most of the radiotracer will leave your body through your urine or stool within a day.
Be sure to flush the toilet right after you use it, and wash your hands thoroughly with soap and water. The amount of radiation in the tracer is very small, so it isn't a risk for people to be around you after the scan.
If you’re breastfeeding, you’ll need to discard the milk you pump for 24 hours after the scan. This is because your breastmilk can have radiation in it from the radiotracer, which can harm your baby. You may wish to pump additional breast milk prior to the scan and safely store it or make alternate plans for your baby to receive nutrition for the one day after the scan.
What are the risks and side effects of a HIDA scan?
A HIDA scan has very few risks, including:
- Bruising at the injection site of the radiotracer.
- Small radiation exposure. During a typical HIDA scan, your radiation exposure is about the same amount of background radiation the average person experiences in a year.
- Possible allergic reaction to medications containing radiotracers used for the scan. This is very rare.
It’s important to tell your healthcare provider if you’re pregnant, think you might be pregnant or are breastfeeding. In most cases, providers don’t perform nuclear medicine tests, such as the HIDA scan, on pregnant people due to potential harm to the developing fetus.
Nuclear medicine imaging, which includes a HIDA scan, provides unique information that providers can’t often get using other imaging procedures, such as ultrasound. Because of this, the benefits of a HIDA scan far outweigh the risks for a non-pregnant person.
