Patient Information

MCUG (bladder function test)


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This gives you information on an MCUG test and how we use it to examine your child’s bladder.

What is a MCUG?

A MCUG (micturating cystourethrogram) is a special X ray test which examines how well your child’s bladder works when they pass urine (wee).

Your doctor will discuss why your child might need to have an MCUG.

Children often get urinary tract infections (UTIs) and usually they are a one-off event.  Occasionally, a child will need a further test to establish the causes of their UTI.  This test can be done via an MCUG, which is usually carried out a few weeks after your child’s UTI has cleared up. 

The MCUG can examine how your child’s bladder stores their wee and how it empties through the urethra. The urethra is the tube which carries the wee out the body from the bladder (where it is stored).

A MCUG can also detect if there is anything structurally unusual in your child’s bladder and urinary tract system.

Contact your GP if you think your child has symptoms of a urine infection (for symptoms of a UTI, see the More information section below).

How is the MCUG carried out?

The MCUG will take place in the radiology department in Kingston Hospital’s Rowan Bentall Wing.

We maintain a calm atmosphere in the radiology department and we use a type of numbing gel to minimise any discomfort for your child.

  • A small soft plastic tube (called a catheter) is placed through the urethra to the bladder.
  • X ray contrast (a special dye that helps show us the inside of your child’s bladder) is passed through the catheter and we fill up your child’s bladder. This makes the child feel as though they need to wee. Babies and children naturally wee when the bladder is full. While the child empties their bladder, we take a series of X rays.

Are there any risks from the MCUG?

The MCUG is usually extremely safe, but there are a number of things you need to know.

RadiationAll X-ray examinations involve exposure to radiation. The amount used in this test is kept to the minimum necessary and is thought to be safe in children. The levels of radiation are similar to natural background radiation which is around us in the environment.
DiscomfortThe insertion of the catheter may initially cause a little discomfort. However, we use an anaesthetic or numbing gel around your child’s urethra to keep them as comfortable as possible.

Your child may also feel a bit uncomfortable when weeing, for a few days after the test. You can give them simple pain killers such as paracetamol to help with pain relief. You can also give ibuprofen (at recommended doses) unless your doctor has specifically told you not to.  Always read the label on the packaging and do not exceed recommended doses for your child’s age group.

Speak to your GP or hospital doctor if your child’s discomfort continues after a few days.
Urinary tract infection (UTI)There is a small risk of a urine infection from this test. We will ask your child to take antibiotics before the procedure, to prevent them getting a UTI. 

If your child is already taking antibiotics, please see the ‘What if my child is already taking antibiotics?’ section below.
Allergic reaction to X ray contrast (special dye)On rare occasions, a child will have a reaction to the X ray contrast, for example a skin reaction or difficulty breathing.

If this happens, the procedure will be stopped immediately and we will treat the allergic reaction.

How do I prepare my child for the MCUG?

Prepare your child for the MCUG in the following ways:

2 weeks before graphic2 weeks before the test, contact your GP to tell them how much your child weighs. Make sure you tell them your child’s current weight.

Your GP will prescribe a 3 day course of antibiotics to reduce the chance of your child catching an infection from the MCUG. 
the day before graphic
Give your child a dose of antibiotics for three days running.
Do this:
on the day before the MCUG
on the actual day of the MCUG
on the day after the MCUG.

What if my child is already taking antibiotics?

If your child is already taking antibiotics, speak to the doctor who has referred your child for the MCUG.  They will tell you what dose your child will need to take during the 3 day period leading up to the MCUG. You can reach hospital consultants via the Paediatrics Admin Team (see Contacts section).

What do I bring with me to my child’s appointment?

On the day of the appointment, bring the following:

  • A spare nappy or pad for your child to wear following the examination.
  • Any toys or dummies or soothers or other things that will help your child to feel comfortable and relaxed.

If your baby is bottle fed, they can have a feed during the procedure, so bring formula milk with you.

What happens on the day of the MCUG?

On the day of the test, attend your appointment at the radiology department according to the instructions in your appointment letter.

  • The radiology team will discuss the procedure and answer any questions you or your child may have. They will ask you to sign a consent form.
  • We use radiation for the MCUG, so only one parent or carer can stay with the child.  We will ask this parent or carer to wear a lead gown during the procedure.
  • If the main parent or carer attending with the child is pregnant, or may be pregnant, we advise you to bring a second person who can support your child during the procedure.
  • Sometimes babies cry during this procedure. This does not mean they are in pain.  It usually means that we are gently holding their arms and legs to stop them from moving during the test.  It is important that the baby or child does not move during the procedure. (Similar to having a photo taken, if the subject moves, the X ray images will be blurred).
  • As soon as the procedure is complete (when your child has had a wee to empty their bladder), we will remove the catheter.
  • You can take your child home as soon as this has been done.

What happens after the MCUG?

Do the following after the scan:

Ensure your child drinks plenty of water that day (or milk or sugar free squash if they prefer).

Make sure they continue their course of antibiotics as prescribed.

The MCUG referring team will make a follow up appointment to discuss the results with you.

When do I seek medical help?

Always contact your GP or call NHS 111 if your baby or child is showing any of the following signs:

  • they are generally unwell
  • they are feeding less than usual
  • they have a temperature above 38C
  • they seem to be unusually sleepy
  • they have changed their toileting habits
  • they have pain or a burning sensation when weeing
  • they have blood in their wee
  • their wee is cloudy or smelly or they have lower tummy pain
  • they are weeing more often than usual or weeing suddenly.

More information

NHS information on UTIs in children (including symptoms)
MCUG (bladder function test) - Kingston Hospital Download PDF


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