What is a micturating cystourethrogram?
A micturating cystourethrogram (MCUG) is a type of imaging test that uses dye to look at your bladder and urethra (the tube that carries urine out of your body). It’s also known as a voiding cystourethrogram (VCUG).
Both ‘micturating’ and ‘voiding’ are other words for passing urine.
This test can detect whether the flow of urine is being blocked or going in the wrong direction.
What does an MCUG involve?
An MCUG is a day procedure carried out in hospital. It takes images while you pass urine, providing information about the flow. A special X-ray contrast dye will be used to show your bladder and urethra more clearly on the images.
Who is it for?
Your kidney doctor may recommend an MCUG if you keep getting urinary tract infections (UTIs). It checks whether UTIs might be caused by blockages in the flow of urine, or whether it’s going up the wrong way.
An MCUG can also help to diagnose conditions babies are sometimes born with, including vesico-ureteric reflux (VUR), which causes urine to travel back up to the kidneys.
Is it safe? Are there any alternatives?
An MCUG is usually carried out when other tests such as an ultrasound haven’t been able to identify the cause of a problem.
Like any procedure, there are a few risks.
Bacteria can be introduced when the catheter is inserted, so there’s a risk of infection, which can be treated with antibiotics. Children may be prescribed antibiotics to prevent infection.
Passing urine may be uncomfortable after the test, or you may need to go to the toilet more often, due to irritation from the catheter. You can take paracetamol to help, and the discomfort should get better within a few days.
Some people are allergic to the contrast dye used in the test. Let your hospital team know if you’ve ever had reactions to X-ray dye. All X-rays use a small amount of radiation so doctors only recommend this type of test if the benefits outweigh the risk.
X-rays can be harmful to an unborn baby. Tell your hospital team if you are pregnant or think you might be.
Where will the MCUG test take place?
In the hospital’s X-ray or radiology department.
A radiologist, a healthcare professional who specialises in X-rays, will perform the test.
What happens before the MCUG?
There isn’t usually any special preparation for this test but follow any guidance you’re given by the hospital healthcare team, and let them know if you’ve had allergic reactions to contrast dye in the past.
What happens during an MCUG?
- You’ll be asked to remove all your clothing, including your underwear, change into a gown, and lie on the X-ray table.
- A healthcare professional will insert a catheter through your urethra into your bladder. The catheter will be covered in local anaesthetic jelly to reduce discomfort.
- The special contrast dye will then be flowed through into your bladder. This won’t be painful, but it may be uncomfortable as it will make your bladder very full.
- After the catheter is removed, you’ll be asked to sit on a special commode and empty your bladder while the radiologist takes X-rays.
- You may be asked to change positions, so they can get different views
- The whole procedure usually takes 30-40 minutes.
What happens immediately after the test?
You should be able to leave straight away and carry on with your usual activities.
What should I expect when I get home?
As there’s a risk of urinary tract infection, the hospital team will explain the signs to be aware of, including a fever, pain on passing urine, and more frequent urination. If you notice these signs, contact your GP as you may need antibiotics.
How will I get the results of the MCUG?
The radiographer will prepare a report and send it to your kidney doctor, who will discuss the results with you in a follow-up appointment.
Is there anything else I need to know?
If you’re given antibiotics before or after the MCUG, it’s important to take the course as prescribed and not stop them early.
Publication date: 02/2026
Review date: 02/2029