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Health Topics: Urodynamic Testing

Children with spina bifida or other neurologic abnormalities often have problems with the urinary system. Some patients have trouble controlling urination (incontinence). In some patients, the bladder is unable to empty when it is full. In other patients, the bladder can empty only partially. Besides causing urine leakage, bladder problems can also cause urine infections and potential kidney damage. In order to tell how well the urinary system works we use urodynamic testing.

Normally two kidneys filter the blood to produce urine. The urine drains down into the bladder where it is stored. The sphincter (control muscle) wraps around the urine channel and squeezes to hold the urine in the bladder. When the bladder is full, the sphincter relaxes to open the urine channel and the bladder muscle squeezes to empty the bladder.

In some patients these two muscles (the sphincter and the bladder emptying muscle) squeeze at the same time. This can cause dangerous pressure in the bladder. In some patients the bladder muscle cannot squeeze to empty the bladder. In order to tell how both of these muscles are working, we do three tests:

  • Uroflow - If a patient can urinate, we do this test to see how much urine comes out of the bladder and how fast the urine empties. The patient urinates into a special toilet to make the measurements. After the uroflow, a catheter is put into the urine channel to see if any urine is left in the bladder.

  • Urethral Pressure Profile - With the catheter in the urine channel we can measure how tightly the sphincter (the control muscle) can squeeze.

  • Cystometrogram (CMG) - A catheter with two openings is put into the bladder. Through one opening we can measure pressure. We can fill the bladder with sterile water through the other opening. A separate catheter is put into the rectum to help us measure pressure in the abdomen. While the catheter is in the bladder we measure how much the bladder holds and how hard the bladder muscle is squeezing. This helps us to know if the bladder fills easily and whether the bladder puts any strain on the kidneys.

Preparation for the Testing

Doing the urodynamic testing while a patient has a urine infection can be dangerous. If your child has cloudy or strong smelling urine or a fever, please call the nurses before the testing (708/216-6266) so that the urine can be checked and any infection can be treated before the urodynamics test.

On the day of the test it is helpful if your child drinks extra fluids about an hour before the test. This will help assure that the bladder is full for the first part of the test (the Uroflow).

Children are often nervous about medical tests. Sometimes they are nervous because they don't know about the testing and how it is done. Sometimes they are afraid that a test will hurt. We will explain the testing ahead of time. Talking to your child about the test may help him/her to ask questions. Once the catheters are in place, the testing takes about 30 to 45 minutes. This can be boring for a child. It may help to bring some books, some music tapes or a videotape. Any activity which your child can to while sitting or lying would be fine.

During the Testing

You are welcome to stay with your child during the testing.

After the Testing

If your child can feel during urination, he/she will probably feel burning and stinging with urination for one to two days. Sometimes children's pain medication (Tylenol, Motrin, etc.) can be helpful. You should use the dose recommended on the package no more often than every four hours. Sometimes sitting in warm water in the bathtub will help.

If your child has fever, pain in the abdomen, nausea, vomiting, cloudy or foul smelling urine, she/he may have a urine infection. Please call the your doctor if any of these symptoms occur.

Testing Results

Even though the testing is finished in an hour or two, analyzing the results will take a few days. You will be contacted by your physician with the results. Please ask questions about the testing and the results and be sure to make a follow-up appointment with your doctor for treatment that may be necessary depending on what the results show.


The information on the Loyola University Health System (LUHS) Web site is for educational purposes only. It is presented in summary form in order to impart general information relating to certain diseases, ailments, physical conditions and their treatments. The information provided through the LUHS Web site should not be used for diagnosing or treating a health problem or a disease, nor is it a substitute for professional care. Should you have any health-care related questions or suspect you have a health problem, you should consult your health care provider. See also Copyright and Disclaimer.

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