Urodynamic testing in children

What is urodynamics?

A urodynamic test measures how the bladder fills, how it holds urine and how it empties. It is a “functional” test of the bladder: ultrasound shows the shape, urodynamics shows how it works.

What is measured?

• bladder volume: how much urine it can hold,
• pressure during filling: whether the bladder stretches elastically or is stiff and builds up pressure,
• involuntary contractions: whether the bladder contracts too early,
• sphincter function: whether it opens during voiding,
• voiding pressure and residual urine.

A high-pressure bladder is dangerous for the kidneys. That is why, in children with neurogenic bladder, this test is the basis of treatment.

How is it done?

1. A very thin pressure catheter is placed through the urethra into the bladder, and a small pressure sensor into the rectum.
2. Adhesive electrodes that measure muscle activity are placed on the perineum.
3. The bladder is slowly filled with a sterile solution, and the pressures are recorded.
4. When the child wants to pass urine, he or she does so.

Sometimes X-ray images are taken at the same time (videourodynamics), which also shows reflux.

Preparation

• There should be no constipation for a few days before the test; if needed, the doctor prescribes a laxative.
• There must be no active urinary tract infection.
• Fasting is not needed. Bring a toy or tablet for your child.
• The child should be awake and as calm as possible, so no anesthesia is given.