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Starship Paediatric Radiology

Public Service, Radiology, Paediatrics

Uroradiology (imaging the urinary tract)

MCU        Micturating Cystourethrography

In order to be able to assess the structure and function of a child’s bladder, and to determine if urine goes backwards from the bladder up to the kidneys (vesico-ureteric reflux), we have to catheterise the bladder by passing a small plastic tube through the child’s urethra. This tube is taped to the child’s inner thigh so that it doesn’t fall out and then used to fill the bladder with clear fluid that contains iodine molecules. This fluid is commonly called contrast or dye; that is because the iodine allows us to see the fluid with x-rays.

When the child micturates (urinates), the bladder contracts and the fluid comes to the outside, around the catheter, and onto the x-ray table where it is soaked up by towels. If there is reflux, we can see the dye go backwards into the ureter(s) which are the tubes that connect the kidneys to the bladder. If the reflux is severe, it will distend the collecting system of the kidney(s). 

For children older than 14 months, we can use premedication prior to the procedure. This usually is midazolam which relaxes the children and which also results in their not remembering the procedure at all, or nitrous oxide.


  • Nothing to eat and drink for 4 hours, if the child is older than 14 months, so that sedation can be given on an empty stomach.
  • Infants under 14 months of age should be given their usual feedings and encouraged to drink fluids.
  • For children younger than 12 months of age who are not already on antibiotics, the referring clinician arranges 3 days of antibiotic coverage prior to the procedure.
  • Children with certain cardiac conditions may require specific antibiotic coverage; if there is any question, the paediatric cardiologist should be consulted.



IVU        Intravenous Urography

In order to see how the kidneys function and the structure of the kidneys, ureters, and bladder, a clear fluid which contains iodine is injected into a vein and radiographs are taken in the x-ray room at specific times thereafter. The fluid (also called contrast or dye because it shows up with x-rays) is filtered out of the blood by the kidneys. It shows up in the collecting systems of the kidneys, mixed with the urine that is being excreted. It then passes down the ureters into the bladder.


  • 0-2 years, nothing to eat or drink for 3 hours prior to the examination.
  • 2 years and older, nothing to eat or drink for 4 hours prior to the examination.



RUG        Retrograde Urethrography

This examination is performed if the child has had trauma to the urethral region or if there is concern regarding narrowing or other abnormality of the urethra, the tube in which urine passes from the bladder to the outside. A small plastic catheter is inserted into the end of the urethra, and a clear fluid which contains iodine is injected into the urethra, through the catheter, so that the urethra can be seen with x-rays and any abnormality documented.

No preparation is needed for this examination.

This page was last updated at 11:51AM on April 14, 2021.