Meckles scan

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

A Meckles scan is used to show your child’s bowel (large intestine) and whether it contains a certain type of tissue that can cause bleeding. The scan works by injecting a substance called an isotope into your child’s veins, which then travels through the blood supply to the bowel.

Various types of scan such as CT, ultrasound and x-rays can show the size and shape of your child’s bowel, but not how well it is 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.

Your child will need to take either ranitidine or cimetidine medicine before the scan, so you will need to make an appointment with your family doctor (GP) or consultant to make sure you have a prescription ready. Your child should take two or three doses just before meals each day for the two days before the scan followed by a final dose on the morning of the scan.

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 GOSH 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.

If your child is under four years old or has a medical condition that means it is difficult to lie still for up to two hours, it is likely that they will need to go to a ward early in the morning before the injection time.

Your child will be given a medicine that will make them sleep during the scan. The ward will contact you about the time of admission and any special instructions.

If you have not heard from the ward three days before the scan, please ring the Nuclear Medicine department.

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 (X-ray) 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, please telephone us beforehand and discuss your concerns with our play specialist.

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 DVD during the scan, so please bring along any favourites. It can also help if your child has a favourite toy to hold as well. Your child will not need to get undressed for the scan.

However, they should wear clothes with as little metal, such as zips or buttons, as possible as this interferes with the scan.

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.

You will be able to stay with your child throughout 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 him or her still.

The scan itself lasts around an hour.

If your child has had sedative medicine, they will return to the ward to wake up fully before you can all go home. 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. These are explained in the next section.

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 his or her body as quickly as possible.

• If your child is toilet-trained, he or she 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.

• Your child should continue to take any medicines as usual. The isotope will not affect them in any way.