• Pediatric Urology Associates

Urodynamics in Children



How is urine made and secreted from the body? The kidneys filter the blood and produce urine which travels down tubes called ureters and enters the bladder where the urine is stored until we have to pee. The bladder is flexible, allowing storage of urine at low pressure and this low pressure system helps to protect our kidneys and helps us remain dry in between going to the bathroom. When the bladder is full, nerve endings send a message to the brain that you need to pee. During urination the bladder muscles squeeze and two sphincters relax to allow complete emptying of the bladder.


Some of the most common conditions that the providers at Pediatric Urology Associates deal with are related to bladder function. We like to break these conditions up into two categories; issues with bladder filling and issues with bladder emptying. Occasionally patients can have abnormalities of both. To name some of the common clinical conditions related to bladder dysfunction are urinary incontinence (leakage of urine), urinary frequency (going too often), urinary urgency (the need to go suddenly), small bladder capacity, weak urinary stream, and urinary tract infections. Patients are evaluated by getting a good urologic symptom history from the parents, doing a physical examination, testing the urine and obtaining a kidney and bladder sonogram. Some patients are asked to complete a voiding diary.


Urodynamics (UDS) is a test that tells us how well the bladder works and why the patient may be suffering from one or more of the above mentioned conditions. It is incorporated into the assessment of patients where more information is necessary to plan the best treatment plan. There are different parts to UDS and your doctor will discuss which parts are relevant to your child's condition

  1. Cystometry or cystometrogram: Used to measure the volume a bladder can hold and at what pressure the muscle is storing this volume. The procedure is relatively short in duration and involves placing a small, soft catheter into the bladder. The bladder is filled through this tube and pressure is monitored both during bladder filling and bladder emptying. Cystometry determines the capacity and compliance of the bladder. There is nothing special needed to prepare for this test. The only contraindication to performing this test is a urinary tract infection; for that reason your provider may prescribe an antibiotic prior to the study.

  2. Electromyography (EMG): Testes the electrical activity of the pelvic floor muscles. Small stick sensors are placed near the rectum to record muscle activity. In normal conditions the muscles of the pelvic fluid are active during bladder filling to help keep us dry. During urination the muscles relax to allow complete emptying of the bladder. Children are often found to have dysfunction of this muscle activity that can be treated with pelvic floor relaxation techniques.

  3. Uroflowmetry: How much urine comes out over a period of time. It is a non-invasive test that tells us how fast the urine comes out. It is done best when the bladder is full. I For that reason your child may be asked to arrive with a full bladder. The post-void residual is recorded after the patient voids to evaluate the extent of bladder emptying. Often the uroflowmetry is done in combination with the EMG, known as flow/EMG study.

  4. On occasion your provider may recommend a videourodynamic (VUDS) assessment of the bladder. VUDS is when standard urodynamics is combined with X-ray imaging. This is more informative in patients with neurogenic bladders, trauma related anatomical defects and in some patients who have had prior surgery.


Results of one or more of these studies should be able to guide therapeutic intervention and help eliminate the child's bladder issues.



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