Why is my child having an MCU?

Your baby or child is having a micturating cysto-urethrogram (MCU) to find out if they have urinary reflux (backflow). If your child is a boy, they may also have an MCU to check for an obstruction of the urethra.

See:  Urinary reflux / VUR (vesico-ureteric reflux) [1], including the section What is the urinary tract and how does it normally work? [2]

What is an MCU?

An MCU is an x-ray test of the bladder as it fills and empties.

Where will the test happen?

The test will take place in the x-ray (radiology) department of your hospital, or at another x-ray (radiology) centre.

What happens during the test?

• your child empties their bladder (if toilet-trained) and lies on an x-ray table
• your child may lie in a cradle so they can be gently restrained for their safety and to make the test quicker
• a nurse or doctor will clean the area around the opening of the urethra (the tube from which urine passes out of the bladder) with a mild antiseptic and then insert a catheter (a soft thin plastic tube) up through the urethra and into the bladder
• the catheter connects to a bottle of contrast (dye)
• the bladder is slowly filled with the dye
• the dye allows the bladder to be seen on x-rays
• infants not toilet-trained will wee around the catheter when the bladder is full
• older children find it harder and require gentle encouragement to wee on the table
• the doctor, or x-ray technologist, will take x-ray pictures while your child is weeing
• the doctor checks these - if they are OK, the catheter is removed
• the solution is washed off before a final x-ray

Will it hurt my child?

The insertion of the catheter can be uncomfortable, more so for boys because of their longer urethra. The doctor or nurse will use a lubricating gel to make the insertion easier. In older boys, local anaesthetic jelly can make the procedure easier.

Apart from this, the test is relatively painless. Children do find having a full bladder uncomfortable, but this passes when they empty their bladder.

Some x-ray departments may offer sedation to children to reduce discomfort and anxiety.

How can I prepare my child?

Many medical procedures or tests can be frightening for children. To help your child feel more comfortable or reassured you can try the following:

• bring comforters or any toys that will reassure your child; a dummy (pacifier) for babies (if they normally suck on one) can be very soothing. It is also helpful to bring something that will catch your child's interest and help them to focus on something else during the procedure (for example, a book that has an element of surprise or requires your child's concentration, such as a 'pop up' book, a 'Where's Wally?' or 'I spy')
• see other suggestions in Helping your child manage their health care treatment / procedure [3]
• many hospitals have play specialists whose job it is to help explain these tests to your child. Play specialists use play to show your child what is going to happen and ways to help them cope
• if your child is old enough, ask if your hospital's x-ray or children's department has a video explaining MCUs, for them to watch; your local branch of Kidney Kids may also be able to help with this
• you will be able to stay with your child for the test and your presence can help reassure them - pregnant mothers cannot stay during the test, and in this case fathers or someone else familiar to your child can be there

Are there any after effects from an MCU?

There are usually no side effects from this test. Some children feel a mild burning while weeing for a short time afterwards (sometimes a day or two). Encourage your child to drink plenty of fluids and this will pass quickly.

In rare cases, children can have difficulty emptying their bladder. If your child has this problem, get them to wee while sitting in a warm bath.

Very rarely, your child may develop a UTI after an MCU. Some x-ray departments may recommend antibiotics around the time of the test to prevent this. Your x-ray department or your child's referring doctor will give you instructions about this.

See: UTI (urinary tract infection) [4].

How do I find out the results?

The x-ray doctor (radiologist) will examine and interpret the x-ray films and make a written report to your doctor. This usually takes several days. Sometimes the radiologist will be able to discuss the results with you at the time of the examination.