A DMSA scan is a type of imaging test that uses special equipment to create pictures of part of the kidneys.
This topic gives general information. The way these tests are performed may vary slightly between different hospitals.
What is a DMSA scan?
A chemical called dimercaptosuccinic acid (DMSA) is injected into your child’s body. This chemical is taken into some cells in their body, such as those in the kidneys. DMSA is linked to a radioisotope. It emits (gives out), a type of radiation (source of energy) called gamma rays.
A scan with a special camera picks up the gamma rays and turns them into pictures.
- Healthy or ‘active’ kidney cells take up the DMSA and emit gamma rays. These are shown on the images as ‘hot spots’ and may be bright or in colour.
- Damaged or less active kidney cells take up less or none of the DMSA and do not emit as many gamma rays. These are shown on the images as darker spots or may not be seen at all.
Why does my child need this test?
A DMSA scan can look at the size, shape and position of your child’s kidneys. It can also check for any scars or abnormal areas of development and find out how well one kidney is working compared to the other.
DMSA scan risks and complications
What are gamma rays?
Gamma rays are a type of ionising radiation, a form of energy. At high levels, they can be dangerous because they can damage cells, the living parts of the body. We are all exposed to ionising radiation – in our homes and workplaces (it is in some construction materials, and it seeps from the ground into buildings), when we eat certain foods, and when we take a flight. However, this is at very low levels.
Are DMSA scans harmful?
Your doctor will carefully consider the risks and benefits of doing this test in your child.
A DMSA scan gives the same amount of radiation (dose) that we are normally exposed to over three months. The radioisotope that is injected into your child’s body becomes inactive after a few hours and is passed out of their body in urine or faeces (poo).
How to prepare your child for a DMSA scan
Your child does not usually need to do anything to prepare for this test, but your doctor will let you know if anything is needed.
The test takes several hours. Because of the long waiting times, you may want to bring books or toys for your child to keep them occupied.
Your doctor may ask whether your child has allergies to any medicines or contrast dye that may be used during the test.
Older girls may be asked if they are having their period, and about the dates of their last period. They may also be asked if they are or could be pregnant. This is because ionising radiation may harm an unborn baby.
Sometimes your child may be asked to go to the toilet just before the scan to make sure their bladder is empty.
Your child may be able to meet with a play specialist, who can use toys to help them prepare for the test.
What happens during the scan?
The DMSA scan takes place in the nuclear medicine department of your hospital. It is performed by a radiographer (a specialist trained in imaging tests) or a technician.
The radioisotope is injected into a blood vessel, using a needle or a small plastic tube called a cannula. This is usually in the hand, arm or foot. Your child may feel a sharp scratch from the needle. A local anaesthetic, a spray or cream, can be put on your child’s skin before inserting the needle or cannula, to make the area feel numb.
It takes some time for the radioisotope to reach the kidneys. Your child will wait for a few hours, and then come back to the nuclear medicine department for the scan.
During the scan, your child lies on a scanning bed. They need to lie still while a large camera above them takes pictures. These show the radioisotope that has been taken up by their kidneys.
What to expect afterwards
Your child can usually go home straight away after the scan.
They may be asked to drink lots of water after the test. This will help ‘flush out’ the DMSA from their body more quickly.
There may be a small amount of DMSA in your child’s urine for 24 hours after the test.
Your child should sit on the toilet to urinate (wee) for the day after the test. Make sure they wash their hands with water and soap.
If your child uses nappies, put used nappies in a separate bag for 24 hours, then throw them away in your normal rubbish. Remember to wash your hands with water and soap.
If your child accidentally wets their clothes or bedding, put these in a separate bag for 24 hours and then wash them as normal.
Pregnant women should avoid direct contact with the child’s urine or faeces for 24 hours.
Getting the results
A report will be sent to your doctor, who will discuss the results with you.