A thin, flexible catheter is inserted into the bladder and sterile isotonic saline is slowly infused. During infusion, bladder pressure is monitored, involuntary contractions are detected, and any sensations experienced by the child are recorded. The bladder's voiding characteristics—such as completeness of emptying and the pressure profile during voiding—are also evaluated.

Test stages:

• Catheterization: A thin, flexible tube (catheter) is gently inserted through the urethra into the bladder to drain any residual urine and then secured with tape.
• Urethral Pressure Profile (UPP): As the catheter is slowly withdrawn, a computer records pressure along the urethra.
• Cystometrogram (CMG): The bladder is filled via the catheter with sterile saline while the computer records bladder pressure. When the bladder is full, the child is asked to void, providing data on voiding pressure and bladder function.
• Urine Flow Rate (Uroflow): The child voids on a special sensor-equipped toilet connected to a computer that measures flow rate and total urine volume in real time.
• Electromyogram (EMG): If a neurologic cause is suspected, electrodes may be placed on the external urethral sphincter to record muscle activity during bladder filling and voiding.

Your pediatric urologist will usually request a urine culture about one week before the scheduled test to ensure there is no urinary tract infection. On the day of the test, your child should arrive with an empty bladder (i.e., have voided just before the appointment). If your child cannot void voluntarily, the bladder may be emptied via catheterization prior to starting the test.

It is also important to explain the purpose and steps of the test to your child—why it is done, what will happen, and how it can help—so they feel more comfortable and the procedure goes smoothly.

A urodynamics test is indicated for children with urinary incontinence or recurrent urinary tract infections that have not responded to simpler treatments such as medication or behavioral strategies. Pediatric urologists order it when detailed assessment of bladder function is needed.

It is especially recommended for children with suspected neurogenic bladder (for example, those with spina bifida) to guide treatment and protect the urinary tract. It also helps assess whether bladder pressure may cause reflux to the kidneys and whether the bladder can generate adequate pressure to empty.

In addition, children with anatomical causes of incontinence—such as bladder exstrophy/epispadias or anorectal malformations—for whom first-line therapies have failed may undergo urodynamics to optimize their treatment plan. The test is generally not performed when any of the following conditions are present:

• Bladder exstrophy
• Myelodysplasia (spina bifida)
• Neurogenic bladder
• Posterior urethral valves
• Spinal cord injury
• Certain urinary tract infections
• Voiding dysfunction

Urodynamic evaluation can be performed in children of any age, from infancy onward. There is no specific age limit.

The urodynamics procedure typically takes about 20–25 minutes to complete.

For special conditions such as neurogenic bladder, annual repetition is recommended. In other cases, it should be repeated only when changes to the treatment plan are needed.

During the test, the child may feel mild discomfort due to the placement of thin catheters in the bladder and, if indicated, the rectum. However, the procedure is not painful and is generally well tolerated.

Urodynamics is usually performed without anesthesia so that bladder function can be assessed under physiological conditions. Anesthesia is rarely used and only in very select cases.

After the test, if your child experiences burning on urination, fever, vomiting, or persistent discomfort, contact your doctor immediately, as these symptoms may indicate an infection or other complication.