Do you have gallbladder problems? Let's talk about the HIDA Scan!

Have you ever felt pain in the upper right side of your abdomen? Or has a doctor told you that you have some kind of problem with your gallbladder? At that time, you may have been asked to have a `HIDA scan` (Hepatobiliary Immunodiacetic Acid Scan). So, you may feel a little scared when you hear this, but don't worry. Today, we will talk about this `HIDA scan` simply, in a way that you can understand.

What is a HIDA scan?

Simply put, a HIDA scan is a special test that looks at how your gallbladder is working. In this, a small amount of a chemical called a radioactive tracer is injected into your body. Then, a special camera is used to watch how it moves through your body. This test is done in a hospital's nuclear medicine department.

To explain a little more, this `HIDA scan` looks at the way bile flows from your liver to your small intestine. We call this path of bile the `biliary system`.

Think about it, your liver makes this digestive fluid called bile. This bile helps us digest the fats in the food we eat. Then, the bile that is made travels through special tubes (biliary ducts) and is stored in the gallbladder. The gallbladder is a small sac located under your liver, on the right side, near your lower ribs. When you eat, this gallbladder contracts (squeezes) and sends the bile stored in it through the ducts to the first part of your small intestine (duodenum), to help digest fats.

Do you understand now? If there is a slight problem somewhere in this process, you can experience various symptoms. That's when this `HIDA scan` can help find the cause. This is also called `cholescintigraphy` and `hepatobiliary scintigraphy`.

What diseases can be detected with a HIDA scan?

Doctors use this `HIDA scan` to detect and assess the extent of these conditions:

• Acute cholecystitis: This is a condition that comes on suddenly. You may experience severe pain in the upper right side of your abdomen and symptoms such as fever. Most often (about 90%) it is caused by gallstones blocking the bile duct.
• Chronic cholecystitis: This is when your gallbladder becomes inflamed and swollen on a regular basis. The pain is less severe than in the acute stage, but the discomfort may come and go. This is often caused by gallstones blocking a bile duct (cystic duct).
• Sphincter of Oddi dysfunction: This is when the sphincter of Oddi, a muscle that acts as a gate for bile and pancreatic juice (enzymes), does not open properly. This causes a backflow of digestive juices. This can cause severe pain.
• Biliary atresia: This is a condition that occurs in newborns. It blocks the flow of bile from the baby's liver to the small intestine. This is a serious, but rare, cause of jaundice in newborns. If it is not corrected surgically within the first two to three months of life, it can cause liver damage.
• Biliary leak: This is when bile leaks out of the bile ducts. When this happens, the surrounding tissue can become swollen, painful, and even infected. This often happens after gallbladder removal surgery, trauma, or liver transplantation.

When do you need a HIDA scan?

Doctors recommend a HIDA scan to check for problems with the liver cells, biliary system, and gallbladder. A doctor may order a HIDA scan if you have any of these symptoms:

• Severe abdominal pain, especially on the right side: This could be due to a sudden inflammation of the gallbladder (cholecystitis). This is the most common reason for a HIDA scan.
• Pain or fever after certain surgeries: If you have had gallbladder removal surgery, upper abdominal surgery, or a liver transplant, you may need a HIDA scan if you have fever and pain afterward.
• Severe jaundice in newborn babies: This may be caused by a life-threatening condition called `biliary atresia`.

Also, if you have a biliary stent placed in your bile duct, you may have a HIDA scan to see if it is working properly. A biliary stent is a thin, hollow tube that is placed in your bile duct to keep it open if it is blocked. If you have had a liver transplant, you may have several HIDA scans to see how your liver is working after the surgery.

Who performs the HIDA scan?

There are three medical professionals involved in performing a HIDA scan. They help set up the scanning equipment, administer the radiopharmaceuticals, and interpret the scan results. They are:

• A doctor who specializes in `nuclear medicine` or `nuclear radiology`.
• Nuclear technologist.
• A medical physicist.

How does the HIDA scan work?

A HIDA scan (hepatobiliary immunodiacetic acid scan) uses small amounts of radioactive substances called radiopharmaceuticals or radiotracers. This is usually injected into your vein.

This `radiotracer` then passes through your liver, gallbladder, and small intestine. This `radiotracer` emits a type of energy called `gamma rays`. Special cameras detect this energy, and a computer uses it to create clear pictures of how your organs and tissues are working.

How do I prepare for a HIDA scan?

Your medical team will give you specific instructions on how to prepare for the HIDA scan. It is very important to follow those instructions exactly. Here is a general guide to preparing:

• If you are pregnant, think you may be pregnant, or are breastfeeding , it is imperative that you tell your doctor before having a HIDA scan.
• Tell your medical team about all the medications you take, including vitamins and herbal supplements. Your doctor may ask you to stop taking some medications before the scan, as they can affect the results of the scan.
• When you come for the scan , remove any jewelry or accessories and leave them at home, or remove them before the scan. These can interfere with the examination.
• If you have a fear of confined spaces (`claustrophobia`), tell us before the test begins. This is because to get the best images, the scanning camera needs to be held a little closer to your body. However, this camera is not like a tube that is closed all the way around, but is open on both sides. It is usually placed right above your stomach, and does not cover your face.
• For a HIDA scan , you must fast for at least four hours (no food or drink except water). If you need to fast for longer than that, your doctor will tell you.
• Newborn babies may need special treatment three to five days before the scan. The staff at the pediatric ward will advise you about this.

Do you have to be put to sleep during the HIDA scan?

You are not usually given anesthesia for a HIDA scan. In fact, some scans require you to move into different positions.

However, if you have difficulty staying still during the scan, or if your baby is being scanned, you or your baby may be given a sedative to help them calm down and feel sleepy. However, it will not make you completely sleepy, you will remain awake.

How long does a HIDA scan take?

A HIDA scan can usually take between one and four hours . Sometimes, you may be asked to come back within 24 hours of the first scan for additional images.

What to expect during a HIDA scan?

There may be slight variations in the way a HIDA scan is performed, depending on which part of your biliary system is being examined. But in general, here's what you can expect:

• You will need to remove the clothes that are covering your stomach area. The hospital will give you a gown to wear instead.
• You will need to lie face up on an examination table.
• A nurse or technician will insert an intravenous (IV) catheter into a vein in your arm or hand, and inject the radiotracer.
• The technician will place the scanning camera over your stomach, close to your body.
• When you start taking pictures, the scanning camera takes a series of pictures. The camera can rotate around you or stay in one place.
• When taking pictures, it's very important to keep the camera in one place without moving. That's when you can get the best quality pictures.
• You may also be asked to change positions between taking pictures. The technologist will tell you that.
• After taking some pictures, the technologist may give you medicine to empty your gallbladder. This may cause a slight cramping pain in your upper abdomen. As your gallbladder empties, they will take more pictures.
• Once all the necessary images have been taken (this can take about four hours), the scan is complete.

Does the HIDA scan hurt?

The HIDA scan isn't that painful. When the radiotracer is given through an IV, you might feel a slight tingling sensation when the needle is inserted into the vein, that's all.

However, if you are having a HIDA scan for a medical condition, you may experience pain due to that condition. For example, conditions such as cholecystitis and sphincter of Oddi dysfunction can cause severe pain. Also, you should not take certain painkillers before the scan, as these medications can affect the function of your biliary system and affect the accuracy of the test.

For example, opiates (such as morphine and codeine) should be stopped at least six hours before a HIDA scan.

What happens after the HIDA scan?

Depending on the reason you had the HIDA scan, you may be able to go home, or you may need to go back to the hospital ward.

You should drink plenty of water for the next 24 hours after the scan. This will help the `radiotracer` to leave your body quickly. In most cases, the `radiotracer` will be excreted from your body within a day, either through urine or stool.

Flush the toilet thoroughly after using it, and wash your hands thoroughly with soap. The amount of radiation in the tracer is very small, so there is no risk to others around you after the scan.

If you are a breastfeeding mother, you should avoid expressing breast milk for 24 hours after the scan. This is because the radiotracer can add radioactivity to your breast milk, which can be harmful to your baby. Therefore, it is best to express some extra breast milk before the scan and keep it safe, or find another way to feed your baby for the day after the scan.

What are the risks and side effects of the HIDA scan?

The risks of a HIDA scan are very low. They are:

• The area where the radiotracer was injected may be slightly bruised.
• There is a small amount of radiation exposure. The amount of radiation you are exposed to during a typical HIDA scan is about the same as the average person is exposed to from the environment in a year.
• It is possible to have an allergic reaction to the radiotracers used in the scan. However, this is very rare .

It is very important to tell your doctor if you are pregnant, think you may be pregnant, or are breastfeeding. In most cases, nuclear medicine tests, such as a HIDA scan, are not performed on pregnant women because they can harm the unborn baby.

Nuclear medicine imaging, including a HIDA scan, provides unique information that other tests, such as ultrasound, cannot. Therefore, if you are not pregnant, the benefits of a HIDA scan far outweigh the small risks.

How long does it take to know the results of the HIDA scan?

A radiologist will look at the images from the HIDA scan, write a report, and tell your doctor the results. Your doctor will then tell you the results. This usually takes less than 24 hours .

What are the results of the HIDA scan?

The information in your HIDA scan results report may vary depending on the reason you had the scan. Typically, the report will describe how the radiotracer moved through your biliary system.

Doctors make the final diagnosis by combining the results of the HIDA scan and other tests, such as blood tests.

The results of a HIDA scan may include:

• Normal: The radiotracer has passed from your liver to your gallbladder and small intestine without any obstruction.
• Slow movement of radiotracer: This could mean that there is a blockage or obstruction somewhere in your bile duct, or that your liver is not working properly.
• No radiotracer seen in the gallbladder: This could mean you have acute cholecystitis, a blockage in the bile duct.
• Abnormally low gallbladder ejection fraction: This is determined by how much bile your gallbladder can eject (ejection fraction) after being stimulated with medication. A gallbladder ejection fraction of 30% to 35% is normal. If this number is abnormally low, it may indicate chronic cholecystitis.
• Radiotracer detected in other areas: If the scan shows that the radiotracer is outside your biliary system, it may indicate a biliary leak.

Remember, whatever your results are, your doctor will explain them to you, so don't be afraid to ask them questions.

Finally, what to know

A `HIDA scan` (Hepatobiliary Immunodiacetic Acid Scan) is an important test to detect certain problems in your liver, bile ducts, and gallbladder. It can be a bit overwhelming to have to undergo such a test. But know that `HIDA scan` is a completely painless test. You can ask your doctor about any questions or concerns you have. Don't worry, doctors are here to help you.

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