THE FORMATION AND PASSAGE OF URINE
One way your body rids itself of waste products is through your kidneys. Your
kidneys filter waste out of your blood and the waste products are turned into urine.
Urine passes from the kidneys through the ureters and into the bladder, where it is
stored until it is time to empty it.
The bladder stretches as it fills up. The stretching sends a message to the
brain to let you know to start looking for a place to urinate. If you do not find a
place right away, the brain will send messages back to the bladder telling it to hold
onto the urine. Once you are able to urinate, the brain send the message to the
bladder to contract and the sphincter muscles to relax. This allows urine to pass
from the bladder to the urethra and out of your body.
WHAT IS A URODYNAMICS STUDY?
An urodynamics study assesses how the bladder and urethra are performing their job of
storing and releasing urine to determine:
 How your child’s bladder holds and passes urine
 The pressure inside the bladder
 The strength of the urethral sphincter(the muscle around the bladder outlet)
The study has three parts:
Uroflow
Measurement of how you urinate.
It will record the amount you urinate, the time it takes to urinate
and the pressure of your urinary stream
Cystometrogram(CMG)
The purpose of this test is to see how well your bladder muscle
stretches as it gets filled and how well you can feel your bladder
filling.
Electromyogram(EMG)
Shows how well your sphincter (outlet) muscles are working and if
they are working with your bladder muscle.
WHAT HAPPENS DURING A URODYNAMICS TEST?
The nurse will ask your child to put on a hospital gown. He or she can cover up with a
blanket. You can stay with your child during the test.
The EMG sticky pads will be placed on your child’s skin. Two pads will be placed on
either side of your child’s anal sphincter (buttocks). The last pad will be placed on your
child’s thigh.
Once the pads are in place your child will be asked to urinate into a special toilet
connected to a computer.
Your child will lie on an exam table. The nurse will wash your child’s private parts with
soap.
Next, the nurse will spread some medicine around the urethra and put a small tube called
a catheter into the bladder through the urethra. The catheter will drain the urine that your
child could not pee out and will be removed when the bladder is empty. The medicine
will make the catheter insertion more comfortable for your child.
Then the nurse will insert 2 small urodynamics catheters-1 into the bladder and the other
will be placed into your child’s rectum. The rectal catheter will feel greasy but it won’t
be uncomfortable.
The nurse will connect these catheters to the urodynamics machine.
The nurse will slowly fill the bladder with water through the catheter. Your child may
feel like peeing and, in fact, may pee on the table. Don’t worry, that’s okay.
The test is done with your child lying down or sitting. After the test is completed, your
child may be asked to pee again in the special toilet. If your child is not able to pee after
the test, the nurse will remove the urodynamics catheters and insert a catheter to drain the
bladder (just like it was done before the test started).
HOW TO PREPARE YOUR CHILD FOR THE TEST
Your child must be free of a urinary tract infection to have this test. Call your doctor if
you think your child may have an infection.
Your child will have to hold very still during the test. Sometimes it helps to distract your
child:
 Bring a book, personal CD player, MP3 player, DVD, or a favorite toy.
 Infants can have their pacifiers or a bottle during the test.
 Have your child count backwards or sing a song.
 Try deep breathing with your child.
 Have your child blow bubbles.
Your child may eat breakfast on the morning of the test. Give lots of fluid because your
child must have a full bladder. Give the fluids unless the nurse indicates otherwise.
If your child takes medications and/or enemas for constipation, be sure that they use them
as directed for at least 4 days before the testing date.
If your child is any medication, ask your child’s doctor if and when the medicine should
be taken on testing day.
It is very important that you tell your child what to expect. Use simple language that
he or she can understand.
WHERE WILL THE TEST BE COMPLETED?
The test will be done at Children’s Hospital of Michigan in the Pediatric Urology Clinic.
Please report to Outpatient Registration on the first floor of the hospital, making sure to
bring all your referral and insurance information. Plan to arrive in the Pediatric Urology
Clinic 30 minutes before your test. Expect to be at the hospital about 2 ½ hours.
If you are more than 30 minutes late for the test appointment, you may need to
reschedule.
WHAT CAN WE EXPECT AFTER THE TEST?
Your child may feel a little stinging when he or she pees.
Have your child drink plenty of water. This will help the stinging go away.
If the stinging lasts more than 2 days, or your child develops a fever, call the doctor.
Your doctor will discuss the results of the test with you at your child’s next clinic visit.