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Urodynamics (YUR oh dye NAM icks) is a series of tests that are done to see how well the urethra (you REE thruh) and bladder are working (Pictures 1 and 2). The muscle strength of the area between the legs is also measured. 


  • Continue all medicines your child is taking before the test. This includes antibiotics.
  • Bring the list of medicines your child is taking. Include the amount and how often your child takes each medicine.

Getting Ready for the Test

  • Explain to your child what will happen during the test. Use words he or she will understand.
  • Parents will stay with the child during the tests.
  • Your child should wear a two-piece outfit, like a T-shirt and jeans for the test. Bring an extra pair of socks and diapers or adult-sized diapers, if used. 
  • If your child is on a regular program of clean intermittent catheterization, please measure urine output for 2 days before the test. Bring this information with you to
    the test.
  • If your child has a history of urinary tract infections, have his or her urine checked 10 days before the appointment. If your child has an infection the day of testing, the test will be cancelled unless he or she has been treated with antibiotics for at least 48 hours.

The Parts of the Test

The urodynamics test is made up of several parts:

  • The uroflow test measures how fast your child can empty his or her bladder.
  • The cystometrogram (CMG) (sis toe MET roe gram) shows how much sensation (feeling) there is in the bladder.
  • The electromyelogram (EMG) (ee leck tro MY lo gram) shows how well the urinary (pee) muscles work.
  • The voiding pressure study measures rate of voiding (how fast pee leaves the bladder), while watching bladder and rectal pressures.

How the Test Is Done

The nurse will help your child lie down on a padded table. Parents will stay with their child while the test is being done.

  • Your child will wear a hospital pajama top and no underwear during the testing.
  • Your child’s “private area” will be cleaned with Betadine®, an antiseptic solution.
  • A sterile plastic tube (catheter) will be put into the urethra. This will remove any urine from the bladder. A numbing gel (local anesthetic) will be used before the catheter is placed.
  • The catheter will cause a feeling of pressure for a short time. It will be left in place until the testing is complete.
  • Another catheter will be put in the rectum.It will measure pressure in the abdominal muscles.
  • Small electrode stickers will be placed on the buttocks. This will not be painful for your child.
  • After the tubes are placed they are connected to a special computer. This will show us how well the bladder is working.
  • The bladder will be filled with water during the test.
  • Once the bladder is full, your child will be asked to pee.
  • When the test is over the tubes and stickers will be removed.

If you have any questions, be sure to ask your child’s doctor or nurse, or call (614) 722-5801.

female and male urinary system inside the body

Urodynamics (PDF)

HH-III-59 11/82, Revised 09/19 Copyright 1996, Nationwide Children's Hospital