A gallbladder scan is an imaging test to look at your gallbladder and see how well it's working. This test may also be called a hepatobiliary iminodiacetic acid (HIDA) scan because the doctor often looks at the bile ducts in the liver at the same time. The liver is near the gallbladder and works closely with it.

A gallbladder scan is a type of nuclear imaging test. This means that a tiny amount of a radioactive tracer is used during the scan. The radioactive tracer (tagging iminodiacetic acid) is absorbed by liver cells and released into bile that travels to the gallbladder. The radioactive tracer sends out gamma rays. These are picked up by the scanner to make a picture of your gallbladder.

The areas of the gallbladder where the radioactive tracer collects in greater amounts are called "hot spots." The areas that don't absorb the tracer and appear less bright on the scan image are referred to as "cold spots."

You may need a gallbladder scan if your doctor thinks you may have gallbladder disease (cholecystitis). Symptoms of gallbladder disease include:

• Sudden severe pain in the upper right area of your belly
• Yellowed skin or eyes (jaundice)

A blood test may also show higher levels of liver enzymes.

A gallbladder scan may also help diagnose blockages in the biliary duct or a bile leak related to complications after gallbladder surgery. It can also tell your doctor how well your gallbladder is working.

Your doctor may have other reasons to recommend a gallbladder scan.

The risk from the radioactive tracer is very low. The amount used in the test is very small. You may feel some slight discomfort when the tracer is injected. Allergic reactions to the tracer are rare, but they may happen.

Lying on the scanning table during the procedure may cause some discomfort or pain for some people.

Tell your doctor if you:

• Are allergic to or sensitive to medicines, contrast dyes, or latex.
• Are pregnant or think that you might be pregnant (the scan may not be safe for the fetus).
• Are breastfeeding (the tracer may contaminate your breast milk).
• Have any medical conditions.

You may have other risks that are unique to you. Be sure to discuss any concerns with your doctor before the procedure.

Certain things may make a gallbladder scan less accurate. These include:

• Having radioactive tracer in your body from another recent nuclear medicine test
• Eating or drinking up to 6 hours before the scan
• Going without food (fasting) for longer than a day (24 hours)
• Getting nutrients as a liquid given through a vein (hyperalimentation)
• Liver disease

Tell your doctor if any of these apply to you.

The scan may also be less accurate if you have a blockage in your gallbladder. The blockage can stop the tracer from reaching your gallbladder. If you have a blockage in the ducts of the gallbladder or liver (biliary tree), the tracer will stop at that point.

• Your doctor will explain the procedure to you. Ask any questions you have about the procedure.
• You may be asked to sign a consent form that gives permission to do the procedure. Read the form carefully and ask questions if anything is not clear.
• Tell your doctor about all medicines you are taking. This includes prescriptions, over-the-counter medicines, and herbal supplements.
• You will be asked to stop eating and drinking (fast) for up to 8 hours before the test. You should not fast any longer than your doctor tells you to. Fasting too little or too long can affect how accurate your test is.
• Tell your doctor if you are allergic to or sensitive to latex, medicines, contrast dyes, or iodine.
• Tell your doctor if you are pregnant or think you may be pregnant, or if you are breastfeeding.
• Follow any other instructions your doctor gives you to get ready.

You may have a gallbladder scan done as an outpatient or as part of your stay in a hospital. The way the test is done may vary depending on your condition and your doctor's practices.

Generally, a gallbladder scan follows this process:

1. You will be asked to remove any clothing, jewelry, or other objects that may get in the way of the procedure.
2. You will be asked to remove clothing. You will be given a gown to wear.
3. An I.V. (intravenous) line will be started in your hand or arm so that you can be given the radioactive tracer.
4. The radioactive tracer will be injected into your vein.
5. You will be asked to lie still on a scanning table. You will need to stay still during the scan. If you move, it may affect the quality of the scan.
6. The scanner will be placed over your belly. The technologist will take a series of images until they can see the gallbladder.
7. In some cases, you may get an I.V. injection of morphine during the scan. This helps move the radioactive tracer into the gallbladder.
8. If the radioactive tracer does not enter the gallbladder within a certain period of time, the scan may be done again within a few hours. This will let the technician see if you have a complete or partial blockage in the biliary tree.
9. When the scan is done, the I.V. line will be removed.

The gallbladder scan is not painful. But you may have some discomfort or pain from lying still during the test. This may be because of a recent surgery or joint injury. The technologist will use all possible comfort measures and do the scan as quickly as possible to minimize any discomfort or pain.

You should move slowly when getting up from the scanner table to avoid any dizziness or lightheadedness.

You may be told to drink plenty of fluids and empty your bladder often for 1 to 2 days after the scan. This will help flush the radioactive tracer from your body.

The medical staff will check the I.V. site for any signs of redness or swelling. Tell your doctor if you see any pain, redness, or swelling at the I.V. site after you go home. These may be signs of infection or another type of reaction.

If you were asked to fast before the scan, you may be offered food and drink after the test. Or you may be told to have a meal.

You may go back to your usual diet and activities as directed by your doctor.

Your doctor may give you additional instructions, depending on your situation.

Before you agree to the test or procedure, make sure you know:

• The name of the test or procedure
• The reason you are having the test or procedure
• What results to expect and what they mean
• The risks and benefits of the test or procedure
• What the possible side effects or complications are
• When and where you are to have the test or procedure
• Who will do the test or procedure and what that person's qualifications are
• What would happen if you did not have the test or procedure
• Any alternative tests or procedures to think about
• When and how you will get the results
• Who to call after the test or procedure if you have questions or problems
• How much you will have to pay for the test or procedure