Micturating cystourethrogram (MCUG)

A micturating cystourethrogram (MCUG) is a scan that shows how well your child’s bladder works. It is used to diagnose why your child may have urinary tract infections.

It is also used to show up any abnormalities with your child’s urinary system. This information sheet from Great Ormond Street Hospital (GOSH) explains about the micturating cystourethrogram scan, what is involved and what to expect when your child has one.

Various types of scan such as CT, ultrasound and x-rays can show the size and shape of your child’s bladder, but not how it is emptying. The results of the scan are used to plan your child’s treatment.

When you receive your appointment letter

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.

The day before the appointment

If your child is already on a routine antibiotic called Trimethoprim, then you will need to do the following:

○ Day before the test: Give a double dose in the morning AND give a double dose in the evening

○ Day of the test: Give a double dose in the morning AND give a double dose in the evening

○ Day after the test: Give a double dose in the morning AND give a double dose in the evening

○ Then go back to your normal dose and carry on as normal

If your child is on a different antibiotic, or not on any course of antibiotics, please contact the clinical team before the test for advice.

It might be helpful to make an appointment with your family doctor (GP) or referring consultant to make sure you have a prescription ready, if in doubt.

This is because inserting the catheter into the bladder can increase the risk of a urinary tract infection and the antibiotics may help to prevent this.

If your child is not currently taking antibiotics to prevent urinary tract infections, they will need to take an antibiotic (trimethoprim) twice a day for three days, from the day before the scan until and including the day after the scan.

If your child is currently taking antibiotics to prevent urinary tract infections, you will need to give double the dose for the three days, either in one single larger dose or give an extra dose in the morning or evening.

The doctor who refers your child for this test will explain all this to you on the day of your appointment.

The day of the scan

Please arrive at the Radiology department at the time stated in your child’s appointment letter.

The person bringing your child to the scan should have ‘Parental Responsibility’ for them. Parental Responsibility refers to the individual who has legal rights, responsibilities, duties, power and authority to make decisions for a child. If the person bringing your child does not have Parental Responsibility, we may have to cancel the scan.

Many of the studies we perform involve the use of x-rays. Legally, we are obliged to ask any girls over the age of 12 whether there is any chance they might be pregnant. This is to protect babies in the womb from receiving unnecessary radiation.

We will also ask mothers or other female carers if they could be pregnant, especially if they are planning to come into the scanning room with their child. If you are pregnant, we suggest you bring another member of the family with you, to be with your child during the scan instead.

It can help if your child has a favourite toy to hold to comfort them during the study. Older children will need to empty their bladders before the scan.

Your child will need to wear a hospital gown for this scan but can keep a vest or t-shirt on underneath. All other underwear or nappies need to be removed once the child is in the examination room, just before the scan starts.

The scan

You will be able to stay with your child throughout the scan. Your child will need to be put onto the scanning bed so that the doctor can insert the catheter into your child’s bladder through the urethra. This does not hurt but it may be a little uncomfortable just while to tube goes in (this usually takes less than a minute). If your child usually has a urinary catheter in place, we will use this for the scan.

Once the catheter is in place, a small amount of contrast medium or dye will be injected through the catheter to fill up the bladder. A contrast medium is a clear liquid that shows up on an X-ray. Babies and young children will naturally pee when the bladder is full. Older children will be given a jug to pee into while lying on the table, when they feel ready.

The radiographer will take a few X-ray pictures while your child is peeing, which you will be able to see on the screen. Your child may need to be held still while these pictures are being taken. When we have enough pictures, the catheter will be removed from your child’s bladder. The scan usually takes about 30 minutes.

After the scan

If your child is not having any further tests or scans, they will be able to get dressed again and you will be free to go home. The radiology doctor will send a report about the scan to your child’s doctor.

Are there any risks?

The contrast medium will not interfere with any medicines your child is taking and no extra precautions need to be taken with dealing with their bodily fluids.

Inserting the catheter into the bladder can increase the risk of a urinary tract infection. Taking a course of antibiotics (or increasing the dose if your child is already taking them) can reduce this risk. Your child needs to start the antibiotics the day before the scan. Please contact your family doctor (GP) or referring hospital doctor to discuss this a week beforehand, so that you have the antibiotics ready to start the day before your appointment.

Compiled by:
The Radiology department in collaboration with the Child and Family Information Group.
Last review date:
June 2020