Health Library

Formal Urodynamics Test

Formal urodynamics are a group of tests used to study the urinary flow, the bladder and bladder pressures.

The test should not be done if your child has a bladder infection.

Before the Test

• Explain the test to your child in words they can easily understand.
• One hour before your scheduled testing time, have your child drink according to the following guidelines so they arrive with a full bladder and can urinate for the test. If your child is catheterized at home or is not toilet-trained, it is not necessary to drink extra liquids (continue with your child's catheterization schedule before the test).
• 3-6 years old: One 8-ounce glass of liquid; no milk or soda pop
• 6-12 years old: Two 8-ounce glasses of liquid; no milk or soda pop
• Adolescents: Three 8-ounce glasses of liquid; no milk or soda pop
• Your child may still eat and follow their normal medicine routine.
• We will answer any questions you or your child may have about the test.
• Allow 45-60 minutes for the test.
• Parents remain in the room during the test.
• There are no shots or needles involved in this test.

During the Test

• Your child will change their clothes and put on a hospital gown. EMG patches, which look like small square bandages, are placed on the outer thighs and buttocks. These patches are attached to wires connected to a computer. They measure your child's muscles, but your child will not feel anything. If your child urinates on their own, they will sit on a portable toilet to urinate. Boys may stand.
• After your child urinates, they will lie on a bed. We will keep your child covered with sheets and blankets to maintain their privacy.
• The nurse places a small, thin, soft tube called a catheter in your child's rectum. Then another small, soft catheter is placed in your child's bladder through the urethra, the tube through which your child urinates. These tubes stay in place until the study is completed.
• After the catheters are in place, the bladder is slowly filled with water. Once full, the urethral catheter is removed, and your child will urinate in the portable toilet again. The rectal catheter and EMG patches are then removed.
• Your child returns to the bed and an ultrasound (diagnostic test using sound waves to get images) of the bladder is done to measure the amount of urine left in the bladder. A clear, cool gel is put on your child's lower belly for the ultrasound. A picture is made by holding a small object which looks like a microphone on the lower belly.
• The test is finished. Your child may then wash and redress.

After the Test

• Your child's doctor will discuss the test results with you at your child's follow-up appointment.
• Encourage your child to drink plenty of fluids and avoid caffeine products for eight hours.