Gall bladder (HIDA) scan

This page explains about gall bladder (HIDA) scans, what is involved and what to expect when your child comes to Great Ormond Street Hospital for the scan.

A gall bladder (HIDA) scan is used to show the size, structure and location of your child’s liver and gall bladder. The scan works by injecting a substance called an isotope into your child’s veins, which then travels to the liver and gall bladder. The isotope is called hepatobiliary imino-Diacetic acid (HIDA) so you may hear the scan referred to as a HIDA scan.

Various types of scans such as CT, ultrasound and X-rays can show the size and shape of your child’s liver and gall bladder, but not how well they are working. The results of the scan are then used to plan your child’s treatment.

If you are unable to keep this appointment, please inform the department at least two weeks beforehand. Sometimes, we can offer the appointment to another child on the waiting list. As so many children and young people need to use our services, we have had to introduce a policy where if a child cancels or does not attend two appointments in a row, we will close their referral and inform their GOSH consultant.

If your child is aged less than one year, they will need to be prescribed a medicine called phenobarbitone for this test. This helps the liver and gall bladder take up the isotope, which increases the accuracy of the test. Please see your doctor to arrange this in plenty of time as the medicine needs to be taken three days before the test.

If you are pregnant or think you could be pregnant, please let us know at least two days before your child is due to come to Great Ormond Street Hospital for the injection. There is a risk that the isotope given to your child could harm your unborn baby, so we advise you to organise another adult to look after your child for the first 24 hours after the scan. If this is not possible, we may have to reschedule your appointment.

If your daughter is 12 years old or older, we will ask her about her periods and any possibility that she could be pregnant.

Your child must not eat or drink anything for four hours before the injection. Please follow these instructions exactly, otherwise the scan may be delayed or even cancelled.

Please arrive at the Radiology department at the time stated in your child’s appointment letter. This is one hour before the injection is due to be given, so your child can have local anaesthetic cream applied. This will numb the skin so the needle does not hurt so much. If your child is apprehensive or scared of needles, a play specialist is available to prepare your child for the scan.

If your child does not want local anaesthetic cream or weighs less than 5kg, please arrive 15 minutes before the injection.

Your child will be able to watch a video during the scan, so please bring along any favourites. It can also help if your child has a favourite toy to hold as well.

Once the local anaesthetic cream has made your child’s skin numb, we will ask you and your child to come to have the injection. The radiographer will put a very small needle in your child’s hand, arm or foot and inject the isotope. Immediately after the injection, they will remove the needle and put a plaster over the area.

Your child will not need to get undressed for the scan. They will need to get up onto the scanning bed and lie very still while some pictures are taken. We can put sandbags around your child to help keep them still. The scan itself lasts around 90 minutes.

Some children will need to have more pictures taken four hours after the injection and again 24 hours after the injection. If this is the case, we will tell you when to come back to the department. If your child is having more pictures taken 24 hours after the injection, you might be able to go home if you live close enough or stay in the patient hotel overnight.

If your child is not having any further scans or tests, you will be free to go home. The radiographer will send a report about the scan to your child’s doctor.

There are no side effects to the scan. The isotope that we inject will not interfere with any medicines your child is taking. The isotope contains a very small amount of radioactivity, similar to the amount we receive from natural background radiation in about six months. This is not a danger to your child as the isotope becomes inactive in the hours following the scan. However, it is necessary to take some precautions for the first 24 hours after the scan, while the isotope is leaving your child’s body.

There is a risk that the isotope could harm the unborn baby, so please follow the instructions earlier to minimise these risks.

For the first 24 hours after the scan:

• Your child should drink plenty of fluids. This will allow the isotope to pass out through their body as quickly as possible.

• If your child is toilet-trained, they should go to the toilet as often as possible. Hand washing afterwards is very important.

• If your child is in nappies, you should change them frequently and dispose of the dirty nappy in an outside bin. Wash your hands thoroughly after nappy changing.

• If you are pregnant or think you could be pregnant, you should avoid contact with your child’s bodily fluids, such as urine (wee), faeces (poo) and vomit.