What is Pediatric Urodynamic study?
Pediatric urodynamic study (UDS) is a group of tests done for the assessment of how well your child’s bladder is functioning.
These tests measure-:
- The functions of the bladder, urethra and pelvic floor muscles
- The bladder pressures while it stores and empties urine
- The urinary flow and the urethral sphincter muscle activity at the same time.
What is the function of the bladder?
The urinary bladder is a reservoir that collects the urine produced by the kidneys and then empties it at the appropriate time. This is a well-coordinated system which governs relaxation and contraction of the bladder and urethral muscles. This system functions to maintain a low pressure inside the bladder and at the same time prevents involuntary leakage of the urine.
The urodynamic study tracks the filling of the bladder and monitors the pressures inside the bladder and simultaneously it also assesses the function of the urinary sphincter muscles with the help of the electromyography (EMG) of these sphincter muscles. Once the bladder is filled it then assesses the voiding pattern.
When is a Pediatric Urodynamic study required?
There are a number of conditions which disrupt this coordination between the bladder and the sphincter muscles like -:
- Anatomical abnormalities: This includes conditions with bladder outlet obstruction likePosterior Urethral Valve, urethral strictures etc. Also in children with anatomic conditions that lead to incontinence, such as bladder exstrophy/epispadias or anorectal malformations, urodynamic studies are recommended as soon as the diagnosis is made and after initial treatments fail to correct the incontinence. Testing helps us inguiding therapy and improves the efficiency of your child’s treatment plan.
- Neurological conditions:This includes conditions like spinal cord anomalies like meningomyelocele, cord teethering etc. In these cases the studies are usually performed during the new-born period, so that therapy can be initiated as soon as possible. Studies are also needed when these children are older, if they haven’t achieved continence.
- Non-neurological conditions like – Neurogenic bladder, voiding dysfunction, incontinence etc. Through these tests we not only diagnose the bladder function problems in the children and also helps us determine the best way to treat the urologic condition, whether through medication, behavioral therapy, surgery or a combination of these. Additionally, through this study, we can also determine the response to the therapy initiated.
How is the study done?
During the procedure, your child will lie on an exam table for the test. Your child’s genital area will be exposed and cleansed to prepare for the catheters to be placed. A special tube called a urinary transducer catheter is put into your child’s urinary passage. It has two tubes on the other end and through one tube your child’s bladder will be filled with normal saline by the UDS machine. The other tube monitors the pressure in the bladder, which is displayed on the UDS machine.
Another small tube will be put into your child’s rectum. This measures rectal pressure during the test. The rectum pushes on the bladder and this can affect bladder pressure.
Having these tubes inserted can be uncomfortable, but it should not hurt. Your child will also have stickers called electrodes gently stuck to the buttocks and hip. The electrodes let us assess your child’s pelvic floor muscles when the bladder is being filled.
During the test, your child may have a feeling of fullness or pressure, similar to what they would feel before urinating with a full bladder. There may be some discomfort when the urinary and rectal tubes are put in and taken out. Your child may have the urge to urinate or have a bowel movement. These feelings will be less if your child is more relaxed. So we counsel the child and the parents before the study, additionally it also helps if the child is viewing his favourite show on a tablet or a mobile phone.
There are 3 phases of the study-:
Voiding phase: Urinary flow rate (also known as the Uroflowmetry)- Your child will be asked to urinate in a special toilet that is attached to a computer that records the actual flow of urine. It measures second-by-second flow and the total volume of urine.
Cystometrogram (CMG): The bladder is filled with warm normal saline through the catheter and, during the filling the computer or the UDS machine monitors the pressures. When the bladder is full, your child will need to urinate with the catheter in place so that the computer can continue to record pressures. This lets doctors monitor bladder pressures, during voiding as well.
Patch Electromyogram (EMG): The patches which are applied to your child’s buttocks will monitor the pelvic floor muscles during the bladder filling and voiding. This is simultaneously recorded by the UDS machine.
Needle Electromyogram (EMG): If your pediatric urologist suspects a neurological cause for your child’s condition, a needle EMG will likely be recommended, which gives an accurate idea about the specific urinary sphincter muscles. For this part of the test, a needle electrode is placed into the external urinary sphincter muscle. The EMG machine will record your child’s sphincter muscle reflexes and responses when the bladder is filled and emptied.
How to prepare for the study?
It is important to prepare your child, explaining why the test is important, what it is designed to accomplish and how it might improve your child’s health. Understanding the purpose of the test and all of its aspects is likely to make the testing easier for your child.
The test will not be done if the child has a urinary tract infection and is showing symptoms, so it should be treated before the test and also the test is performed under the cover of antibiotics.
Your child can eat and drink as usual before the test.
If possible, please encourage your child to have a bowel movement on the morning of the test. We usually give medications 1 or 2 days before the test to make sure that the child has an empty rectum. If the child is on a bowel management program then it needs to be completed the evening before or early morning on the day of the test. Constipation can affect the accuracy of the test.
You need to give all the medications the child is taking and also to get all the previous investigation reports.
What happens after the test?
When the test is complete, all the tubes and sticky pads will be removed. Your child may have some burning when they urinate after the test. This is normal and should improve the more often your child urinates. It should go away within 24 hours. Make sure your child drinks plenty of fluids. If your child is having any pain, you may give Crocin. A warm bath or shower may also help if they are having discomfort when they urinate.
When are the results of the tests available?
The tests are performed in the urodynamic suite, which have all the equipment installed there, along with the private toilet which is connected to the machine. There is urodynamic technician and a urodynamic nurse who help us in performing the study. The final interpretation is given after the study and further plan of action is explained.